Wire up ?view=<id> so embedded instances can open on a specific view

[paolino]

Context

`zk-lab` publishes a single Turtle graph with three SKOS concept schemes (Culture, Abstractions, Challenges). Each chapter page in the MkDocs site needs to embed the graph-browser opened on the corresponding chapter.

A chapter filter is already expressible as a SPARQL view in `data/queries.json` (tagged `"view"`) — so no dedicated scheme/filter param is needed. The scheme is the query.

What is missing is a way to select the initial view via URL, so each iframe can open on its own chapter without user clicks inside the browser.

What works today

• `?repo=owner/repo` deep-links to the data (`src/FFI/Url.js`, `src/Main.purs:100-104`, `src/RepoDiscovery.purs:94-111`).
• Views are defined in `data/queries.json` with `"view": true` and chosen post-load from the in-app picker (`src/Viewer.purs:291-303`).

What doesn't work

• `?view=` is dead code. FFI functions `getViewParam` / `setViewParam` exist in `src/FFI/Url.js:17-31` and `src/FFI/Url.purs` but are never referenced by any caller.

Request

• P1: wire up `?view=` to select the initial view on load, matching entries in `data/queries.json` (or `data/views/index.json`) by id or label. Round-trip it on navigation so sharable links survive selection.
• P2 (optional): `?embed=1` — hide the repo-manager panel and outer chrome, for iframe use. Not blocking; a plain iframe works today, just with extra chrome.

Use case

```html

<iframe src=\"https://lambdasistemi.github.io/graph-browser/?repo=lambdasistemi/zk-lab&view=culture\"></iframe> \`\`\`

opens the browser on this repo's `culture` SPARQL view.

Not blocking

`zk-lab` can ship its MkDocs site today by embedding the full graph and instructing readers to pick the chapter from the picker. Landing this issue replaces that instruction with a preselected view.