feat(ui): add browser console served by the daemon

Introduce a minimal operations console reachable on a dedicated UI port
(default 8081), kept separate from the OpenAI-compatible API port.

- ts_web/ holds the SPA shell (index.html, app.css, vanilla app.js) with
  sidebar navigation for all views from readme.ui.md and a working
  Overview page backed by a new /_ui/overview JSON endpoint.
- scripts/bundle-ui.ts walks ts_web/ and emits ts_bundled/bundle.ts, a
  single generated module exporting every asset as base64. Mirrors the
  @stack.gallery/registry pattern so deno compile binaries embed the
  entire UI with no external filesystem dependency at runtime.
- ts/ui/server.ts (UiServer) serves assets from either the bundled map
  (default, prod) or directly from ts_web/ on disk (dev). The source is
  chosen per-config and can be overridden by UI_ASSET_SOURCE=disk|bundle.
  SPA fallback routes unknown extensionless paths to index.html.
- IModelGridConfig.ui block with enabled/port/host/assetSource defaults;
  config init writes the block, the normalizer fills in defaults on
  load, and the daemon starts/stops the UI server alongside the API.
- deno.json gains a bundle:ui task; compile:all now depends on it so
  released binaries always contain an up-to-date bundle. dev task sets
  UI_ASSET_SOURCE=disk for hot edits.
- ts_bundled/ is gitignored (generated on build).
- test/ui-server.smoke.ts exercises bundle and disk modes end to end
  (index, app.js, SPA fallback, /_ui/overview, 404).

deno.json

@@ -4,9 +4,10 @@
   "exports": "./mod.ts",
   "nodeModulesDir": "auto",
   "tasks": {
-    "dev": "deno run --allow-all mod.ts",
+    "dev": "UI_ASSET_SOURCE=disk deno run --allow-all mod.ts",
+    "bundle:ui": "deno run --allow-read --allow-write scripts/bundle-ui.ts",
     "compile": "deno task compile:all",
-    "compile:all": "bash scripts/compile-all.sh",
+    "compile:all": "deno task bundle:ui && bash scripts/compile-all.sh",
     "test": "deno test --allow-all test/",
     "test:watch": "deno test --allow-all --watch test/",
     "check": "deno check mod.ts",