docs: convert repository to the standard layout

.mise.toml

@@ -3,3 +3,4 @@ go = "1.25"
 just = "latest"
 node = "22"
 bun = "latest"
+uv = "latest"

AGENTS.md

@@ -0,0 +1,55 @@
+# AGENTS.md
+
+Test: `just test` | Before committing: `just ready`
+
+Read @CONTRIBUTING.md first. It covers prerequisites, setup, project structure,
+code standards, testing, input validation, and how to add an API domain — all of
+which apply to agents exactly as they apply to people. This file carries only
+what is specific to agents.
+
+## Running tools
+
+Invoke tools through `mise`, not from your path:
+
+```bash
+mise exec -- just test
+```
+
+`mise` is active in a person's shell and supplies the versions `.mise.toml`
+declares. An agent's shell has no activation, so a bare `just` resolves to
+whatever is installed globally — usually an older version.
+
+The symptom is a check that fails here and passes in continuous integration, on
+a file nobody edited. When that happens, establish which version ran before
+treating the failure as real.
+
+## Never build with the Go toolchain directly
+
+`go build ./...` and `go test ./...` fail in this repository. The UI is embedded
+via `//go:embed dist/*`, which requires `ui/dist/` to hold files at compile
+time. Use `just build`, `just test`, or `just ready` — each builds the UI first.
+See @CONTRIBUTING.md under "Building and running".
+
+## Where the rules come from
+
+Repository layout, shared tooling, and the Go conventions this repository
+follows are specified in [osapi-io/specs](https://github.com/osapi-io/specs).
+When a convention here and the specification disagree, the specification wins —
+say so rather than following the code.
+
+## Commit trailer
+
+When committing via Claude Code, end the message with:
+
+```
+🤖 Generated with [Claude Code](https://claude.ai/code)
+
+Co-Authored-By: Claude <noreply@anthropic.com>
+```
+
+## Task tracking
+
+Implementation planning and execution uses the superpowers plugin workflows
+(`writing-plans` and `executing-plans`). Plans are working notes and are not
+committed — the design record for a change lives in
+[osapi-io/specs](https://github.com/osapi-io/specs).