nginx: serve mgmt /static/ assets from disk (no Flask round-trip)

Generated management-domain server blocks now include a
location /static/ aliasing webui/static/ with Cache-Control: no-cache
(ETag revalidation -> 304), nosniff, and a restrictive CSP, so SPA
asset requests no longer reach Flask. Flask's static route remains
the dev-mode fallback.

- lib/nginx.py + daemon/handlers/nginx.py: static_root render context
  (the handler renders the template directly, so both paths need it)
- template: alias uses a trailing slash (nginx concatenates the
  location remainder onto the alias value)
- install.sh: a+rX on webui/static plus execute-up-the-parent-chain
  so the nginx worker (www-data) can traverse repo-in-$HOME installs
- tests: mgmt static location assertions (positive + non-mgmt negative)
- docs: AGENTS.md, architecture.md, security.md static-serving notes

docs/architecture.md

@@ -337,7 +337,7 @@ The web UI is a single-page application built on **Hoover**, a custom lightweigh
 
 ```
 Client requests / ──→ nginx ──→ Flask (serves index.html)
-Client loads /static/app.js ──→ Hoover initializes, checkSession() (401 with valid refresh token → one refresh) → if no valid session, render #login
+Client loads /static/app.js ──→ served by nginx directly from disk (mgmt `location /static/` alias, no Flask round-trip) ──→ Hoover initializes, checkSession() (401 with valid refresh token → one refresh) → if no valid session, render #login
 Authenticated ──→ mounts #sidebar and #main render roots
 apiFetch() ──→ injects Authorization: Bearer <token> header ──→ Flask REST API
 Flask before_request ──→ validates JWT from header, checks blacklist, verifies permissions
@@ -348,7 +348,7 @@ Token expiry ──→ refreshScheduler() ──→ POST /api/auth/refresh ─
 WS connect ──→ snapshot (full state) / versions + tick deltas (per-subsystem data) ──→ modelSet() patches model in place ──→ render engine VDOM-diffs and patches only changed DOM nodes
 ```
 
-The SPA entry point only serves `index.html` at `/`. All other paths return 404. Non-API, non-static paths are not served by Flask — the client-side router handles all navigation via hash changes. A dedicated `/vendor/<path>` route serves vendored JS libraries.
+The SPA entry point only serves `index.html` at `/`. All other paths return 404. Non-API, non-static paths are not served by Flask — the client-side router handles all navigation via hash changes. A dedicated `/vendor/<path>` route serves vendored JS libraries. On the management domain, nginx serves `/static/` directly from `webui/static/` via a `location /static/` alias in the generated server block, so asset requests never reach Flask in production; Flask's static route remains as the dev-mode fallback.
 
 ### Component Model
 
@@ -356,7 +356,7 @@ Each route is a `definePage()` component with reactive state, async data loading
 
 ### No Build Step
 
-All JavaScript is served as ES modules. Cache invalidation is handled via HTTP cache-control headers. Dev mode (`VACUUM_WALL_DEV`) disables aggressive static asset caching.
+All JavaScript is served as ES modules. Cache invalidation is handled via HTTP cache-control headers: the management domain's `/static/` assets carry `Cache-Control: no-cache` (browsers revalidate every load; unchanged files return 304 via nginx's built-in ETag), so updates are picked up on the next page load. Dev mode (`VACUUM_WALL_DEV`) uses short TTLs instead.
 
 ### WebSocket Data Streaming