docs(site): add GitHub Pages landing site

.gitattributes

@@ -1,3 +1,8 @@
 # Shell scripts must keep LF endings so their shebang works after checkout
 # on machines with core.autocrlf enabled.
 *.sh text eol=lf
+
+# Landing site: normalize to LF and exclude from language stats; index.html is
+# generated by site/build.js.
+site/** text eol=lf linguist-documentation
+site/index.html linguist-generated

.github/workflows/pages.yml

@@ -0,0 +1,96 @@
+name: Pages
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - 'site/**'
+      - '.github/workflows/pages.yml'
+
+  pull_request:
+    branches:
+      - main
+    paths:
+      - 'site/**'
+      - '.github/workflows/pages.yml'
+
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: pages-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  pages-build:
+    name: pages-build
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5.1.0
+        with:
+          persist-credentials: false
+
+      - name: Stage site
+        shell: bash
+        run: |
+          set -euo pipefail
+          mkdir -p _site/licenses
+          cp site/index.html _site/index.html
+          cp site/licenses/OFL-ChakraPetch.txt _site/licenses/
+          cp site/licenses/OFL-IBMPlexMono.txt _site/licenses/
+
+      - name: Set up Node.js
+        uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: '24'
+          package-manager-cache: false
+
+      - name: Install site dependencies
+        working-directory: site
+        shell: bash
+        run: npm ci --ignore-scripts --no-audit --no-fund
+
+      - name: Verify committed index.html matches build output
+        working-directory: site
+        shell: bash
+        run: |
+          set -euo pipefail
+          node build.js
+          if ! cmp -s ../_site/index.html index.html; then
+            echo "::error file=site/index.html::Committed index.html does not match build.js output. Run npm ci and node build.js in site/, then commit index.html."
+            git diff --stat -- index.html
+            exit 1
+          fi
+          changes="$(git status --porcelain --untracked-files=all -- .)"
+          if [ -n "$changes" ]; then
+            echo "::error::Building the site left uncommitted changes under site/."
+            printf '%s\n' "$changes"
+            exit 1
+          fi
+
+      - name: Upload Pages artifact
+        uses: actions/upload-pages-artifact@fc324d3547104276b827a68afc52ff2a11cc49c9 # v5.0.0
+        with:
+          path: _site/
+
+  pages-deploy:
+    name: pages-deploy
+    needs: pages-build
+    if: github.ref == 'refs/heads/main'
+    runs-on: ubuntu-latest
+    permissions:
+      pages: write
+      id-token: write
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@368f82528645a54fb793d4d04e342629a3f51346 # v5.0.1

README.md

@@ -589,6 +589,7 @@ link.LinkObjects.Add(new LinkObject("/orders/1"));
 
 ## Additional Resources
 
+- **Project Site:** [brenpike.github.io/Chatter.Rest.Hal](https://brenpike.github.io/Chatter.Rest.Hal/)
 - **Source Code:** [GitHub Repository](https://github.com/brenpike/Chatter.Rest.Hal)
 - **Core Library:** [Resource.cs](https://github.com/brenpike/Chatter.Rest.Hal/blob/main/src/Chatter.Rest.Hal/Resource.cs)
 - **Code Generators:** [Source Generator Project](https://github.com/brenpike/Chatter.Rest.Hal/tree/main/src/Chatter.Rest.Hal.CodeGenerators)

site/README.md

@@ -0,0 +1,80 @@
+# Chatter.Rest.Hal landing site
+
+This directory holds the source for the project landing page, published at
+https://brenpike.github.io/Chatter.Rest.Hal/.
+
+## Files
+
+- `index.src.html` is the hand-edited page source.
+- `build.js` inlines the web fonts into `index.src.html` and writes `index.html`.
+- `index.html` is committed build output. Never edit it by hand.
+- `licenses/` contains the font license texts.
+
+## Rebuilding
+
+```sh
+cd site
+npm ci
+node build.js
+```
+
+Commit the changed source and the regenerated `index.html` together.
+
+## Deployment
+
+The GitHub Pages source for this repository is set to GitHub Actions.
+`.github/workflows/pages.yml` publishes the committed `index.html` and the
+`licenses/` texts. Before publishing it reinstalls the pinned font packages
+(`npm ci`), runs `build.js`, and fails if the output differs from the committed
+`index.html`, so rebuild and commit `index.html` before merging.
+
+- A push to `main` that touches `site/**` or the workflow file runs `pages-build`
+  and then `pages-deploy`.
+- A pull request against `main` that touches the same paths runs only
+  `pages-build`. It never deploys.
+- A manual workflow dispatch deploys only when run from `main`. From any other
+  branch or tag, `pages-deploy` is skipped and the published site does not change.
+- Runs are serialized per ref, so at most one run per ref is in progress.
+  GitHub does not guarantee the order in which queued runs start, so an older
+  commit can occasionally deploy after a newer one.
+- Each run publishes the commit it was started for, and the last deploy to
+  finish wins. The workflow does not check that this commit is still the tip
+  of `main`.
+- Re-running an older `main` run redeploys that run's commit. This is the
+  intended rollback path.
+- If the published site looks stale, re-run the newest `main` run or push to
+  `main`.
+- A new push to a pull request cancels that pull request's in-progress run.
+
+## Fonts
+
+The page embeds Chakra Petch and IBM Plex Mono, both licensed under the SIL Open
+Font License 1.1. The license texts are in `licenses/OFL-ChakraPetch.txt` and
+`licenses/OFL-IBMPlexMono.txt`.
+
+## Capture hooks
+
+The page intentionally keeps the `window.seek(t)` hook and its related globals
+(`__seam`, `__ready`, `render`). They allow deterministic frame-by-frame capture
+of the page animation for screenshots and recordings. Do not remove them.
+
+## Review checklist
+
+- **Accessibility:** the landing copy is in the accessibility tree at every width.
+  `.mcopy` is the text source and is never `display:none`. The animated stages stay `aria-hidden`.
+- **Motion:** rendering is demand-driven. `requestRender()` is the only scheduler and the page
+  calls `requestAnimationFrame` nowhere else. A frame requests another frame only while
+  `animating()` is true, and every timeline is clamped to its settle time, so an idle page runs
+  no frames and makes no DOM writes.
+  - `sample()` is the only live writer of render state. Every input it reads (clock, scroll position,
+    viewport height, mode, reduced motion, Act-2 start) must have a subscription that calls `requestRender()`.
+  - Event handlers never write render state. They only update anchors (such as the Act-2 start time)
+    and call `requestRender()`.
+  - Every environment input (width, reduced motion, resize) goes through `applyPresentation()`, the
+    only reader of `.matches`. Never decide presentation once at load.
+  - Reduced motion shows the end-state frame and schedules no animation frames.
+  - After `seek()`, frames never continue on their own. Environment changes re-layout and re-render only.
+  - The capture hooks (`seek()`, `render`) render synchronously and bypass the scheduler.
+- **HAL fidelity:** the Act-2 JSON pane must be token-identical to real serializer output (whitespace aside)
+  for the Act-2 builder code. Verify against real Chatter.Rest.Hal output when either changes.
+- **Render parity:** unrelated edits change no pixels.

site/build.js

@@ -0,0 +1,11 @@
+const fs=require('fs'),path=require('path');
+const d=__dirname;
+const f=(p)=>fs.readFileSync(path.join(d,'node_modules/@fontsource',p)).toString('base64');
+const face=(fam,w,file)=>`@font-face{font-family:"${fam}";font-weight:${w};font-style:normal;font-display:block;src:url(data:font/woff2;base64,${f(file)}) format("woff2")}`;
+const css=[
+ ...[400,500,600,700].map(w=>face('Chakra Petch',w,`chakra-petch/files/chakra-petch-latin-${w}-normal.woff2`)),
+ ...[400,500,600].map(w=>face('IBM Plex Mono',w,`ibm-plex-mono/files/ibm-plex-mono-latin-${w}-normal.woff2`)),
+].join('\n');
+let h=fs.readFileSync(path.join(d,'index.src.html'),'utf8').replace('/*FONTS*/',css);
+fs.writeFileSync(path.join(d,'index.html'),h);
+console.log('index.html',(h.length/1024).toFixed(0)+'KB');