feat(ui): the viewer's screens as @colbymchenry/codegraph-ui, behind one adapter (CG-61)

`ui/src` now builds two ways from one tree: the static app `codegraph ui`
serves, and — via `svelte-package` — a Svelte library the Pro app imports.
A forked component would be a second answer to the same question about the
same graph, so there is no fork.

Everything a screen knows arrives through a `GraphAdapter`: eleven methods
answering the wire shapes verbatim, with `createHttpAdapter()` (the loopback
JSON API) as the default and a host's in-process engine reads as the point.
`lib/api.ts` became a one-line-per-call facade over it, which is why no call
site in the views changed. The payload types moved to `lib/wire.ts` — no
imports, no runtime — so a host can depend on the vocabulary alone.

Two more seams and one guard:

- `lib/navigation.ts` holds the href builders behind a `NavigationDriver`, so
  a host addresses its own URL space. The app's half — the hash parser and the
  live route, which attach window listeners at module scope — stays in
  `router.svelte.ts` and is pruned out of the package: rendering a Symbol view
  must not install a hash router in somebody else's application.
- `lib/theme.css` carries the design tokens and maps Svelte Flow's `--xy-*`
  variables onto them, so a host never sees library defaults. Dark now also
  answers to a bare `[data-theme]`, which is how `<CodegraphUi theme>` themes
  a container rather than the document.
- `scripts/check-ui-package.mjs` prunes the app's shell, resolves the
  extensionless specifiers svelte-package leaves behind, and asserts that
  nothing but `lib/adapter.js` reaches the network.

The search box, its keyboard and its panel are one component now
(`SearchPalette`), because splitting them is what breaks a palette.

`__tests__/ui-package.test.ts` mounts the three screens from the package entry
against a mock adapter in jsdom; it runs as a second vitest project so the
`browser` resolve condition it needs cannot reach the engine's suites.

Versioned with the engine. Prepared, not published: `private: true` is the
guard and `pack-npm.sh` only packs a tarball under CODEGRAPH_PACK_UI=1.

package.json

@@ -22,6 +22,7 @@
   "scripts": {
     "build": "tsc && npm run copy-assets && npm run build:ui && node -e \"require('fs').chmodSync('dist/bin/codegraph.js', 0o755)\"",
     "build:ui": "npm run build --workspace ui && node scripts/check-ui-build.mjs",
+    "build:lib": "npm run build:lib --workspace ui",
     "preuninstall": "node dist/bin/uninstall.js",
     "copy-assets": "node -e \"const fs=require('fs');fs.mkdirSync('dist/db',{recursive:true});fs.copyFileSync('src/db/schema.sql','dist/db/schema.sql');fs.mkdirSync('dist/extraction/wasm',{recursive:true});fs.readdirSync('src/extraction/wasm').filter(f=>f.endsWith('.wasm')).forEach(f=>fs.copyFileSync('src/extraction/wasm/'+f,'dist/extraction/wasm/'+f))\"",
     "dev": "tsc --watch",
@@ -53,9 +54,11 @@
     "web-tree-sitter": "^0.25.3"
   },
   "devDependencies": {
+    "@sveltejs/vite-plugin-svelte": "^4.0.4",
     "@types/better-sqlite3": "^7.6.0",
     "@types/node": "^20.19.30",
     "@types/picomatch": "^4.0.2",
+    "jsdom": "^25.0.1",
     "typescript": "^5.0.0",
     "vitest": "^2.1.9"
   },