security: close capability, CSP and auth-bridge holes

capabilities/default.json
- Drop every `store:*` grant. `@tauri-apps/plugin-store` has no caller in
  `app/src`, and the plugin's `resolve_store_path` is a `PathBuf::push` against
  AppData — `push` discards the base for an absolute path, so the grant was an
  arbitrary host read/write from the webview.
- Replace `opener:default` with a scoped `opener:allow-open-url` (http/https
  only). That drops `reveal_item_in_dir`, which the plugin does not scope-check
  and nothing here calls, and the unused mailto:/tel: scope.
- Record the unscopable `drag:allow-start-drag` residual risk in `description`.

tauri.conf.json
- Add `form-action 'none'`, `base-uri 'none'`, `object-src 'none'`.
  `form-action` has no `default-src` fallback, so an injected auto-submitting
  form was unblocked even though `script-src 'self'` blocks XSS.
- Remove the dead `asset:` / `https://asset.localhost` img-src and `data:`
  font-src grants; `blob:` stays (the file viewer uses it).

auth_bridge
- The reserved-port set covered only this project's mappings and the two
  browser-view ranges. It now also covers the gateway, STT and web-terminal
  host ports (configured value and shipped default, read off the settings
  models) and every other project's published host port. A container binding
  container-loopback 4000 / 9876 / 7681 while those services were stopped had
  that port mirrored onto the host, unauthenticated, within one poll.
- Gate the host listener on fetch metadata: refuse a request that is a
  cross-site sub-resource, allow navigations (the OAuth redirect) and anything
  without `Sec-Fetch-*`. Non-HTTP connections are classified from their first
  line and forwarded verbatim. Residual risk is spelled out in the module docs.
- Bound the forwards: max concurrent connections per port, a first-byte
  deadline enforced before any `docker exec` is created, and an idle timeout.

browser_view/mod.rs
- `pick_viewer_port` reads procfs with `/usr/bin/cat`, not a bare `cat` the
  container can shim via its writable PATH entry.
- Treat port choice as check-then-bind: walk to the next free candidate when
  the viewer does not come up, instead of failing the start.

BrowserTab.tsx
- Sandbox the viewer iframe. Container-controlled content could `top.location`
  the app's webview away. `allow-top-navigation*` and
  `allow-popups-to-escape-sandbox` are deliberately absent.

HelpDialog.tsx
- Escape the quote characters in the entity pass and escape captured attribute
  values. `href="$2"` with `$2` = `[^)]+` let remote GitHub markdown close the
  attribute and open another, in a document rendered with
  `dangerouslySetInnerHTML`.

web_terminal/terminal.html
- SRI hashes plus `crossorigin` on the three jsdelivr bundles and the
  stylesheet, and a CSP for the page — it is served 0.0.0.0 behind a permissive
  CORS layer and nothing else gives it one.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GBq2rGum6GX7xXgsas1fDc

app/src-tauri/tauri.conf.json

@@ -22,7 +22,7 @@
       }
     ],
     "security": {
-      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' blob: asset: https://asset.localhost; font-src 'self' data:; connect-src 'self' ipc: http://ipc.localhost; frame-src http://127.0.0.1:47820 http://127.0.0.1:47821 http://127.0.0.1:47822 http://127.0.0.1:47823 http://127.0.0.1:47824 http://127.0.0.1:47825 http://127.0.0.1:47826 http://127.0.0.1:47827"
+      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' blob:; font-src 'self'; connect-src 'self' ipc: http://ipc.localhost; frame-src http://127.0.0.1:47820 http://127.0.0.1:47821 http://127.0.0.1:47822 http://127.0.0.1:47823 http://127.0.0.1:47824 http://127.0.0.1:47825 http://127.0.0.1:47826 http://127.0.0.1:47827; form-action 'none'; base-uri 'none'; object-src 'none'"
     }
   },
   "bundle": {