v2.0.0: BooCoder frontend — chat pane + diff pane + session picker

Phase 3 of v2.0. React + Vite SPA at apps/coder/web/ served by
the coder Fastify server via @fastify/static with SPA fallback.

Chat pane: message list via WS streaming (useSessionStream hook),
input bar, POST /api/sessions/:id/messages on submit, markdown
rendering via react-markdown + remark-gfm, inline tool-call display.

Diff pane: fetches GET /api/sessions/:id/pending, shows pending
changes with file path + operation badge (create/edit/delete),
before/after diff for edits, Approve/Reject per change and
Approve All/Reject All buttons.

Layout: fixed two-pane split (chat 60%, diff 40%). Dark theme
(bg-zinc-900). Desktop-first for v2.0.0.

Session picker (Home page): lists projects and sessions from the
shared DB. No CRUD — use BooChat's UI for that.

Dockerfile updated: builds web app in builder stage, copies dist
to runtime. index.ts registers fastifyStatic + SPA fallback route.

Tailwind v4, React 18, TypeScript strict. ~20 new files, ~370KB
built output. Functional developer tool UI, not polished consumer
product — Phase 7 (v2.0.3) handles polish.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pnpm-lock.yaml

@@ -80,6 +80,49 @@ importers:
         specifier: ^3.0.0
         version: 3.2.4(@types/debug@4.1.13)(@types/node@20.19.41)(lightningcss@1.32.0)(msw@2.14.6(@types/node@20.19.41)(typescript@5.9.3))
 
+  apps/coder/web:
+    dependencies:
+      lucide-react:
+        specifier: ^1.16.0
+        version: 1.16.0(react@18.3.1)
+      react:
+        specifier: ^18.3.1
+        version: 18.3.1
+      react-dom:
+        specifier: ^18.3.1
+        version: 18.3.1(react@18.3.1)
+      react-markdown:
+        specifier: ^10.1.0
+        version: 10.1.0(@types/react@18.3.28)(react@18.3.1)
+      react-router-dom:
+        specifier: ^6.26.0
+        version: 6.30.3(react-dom@18.3.1(react@18.3.1))(react@18.3.1)
+      remark-gfm:
+        specifier: ^4.0.1
+        version: 4.0.1
+    devDependencies:
+      '@tailwindcss/postcss':
+        specifier: ^4.3.0
+        version: 4.3.0
+      '@types/react':
+        specifier: ^18.3.3
+        version: 18.3.28
+      '@types/react-dom':
+        specifier: ^18.3.0
+        version: 18.3.7(@types/react@18.3.28)
+      '@vitejs/plugin-react':
+        specifier: ^4.3.1
+        version: 4.7.0(vite@5.4.21(@types/node@20.19.41)(lightningcss@1.32.0))
+      tailwindcss:
+        specifier: ^4.3.0
+        version: 4.3.0
+      typescript:
+        specifier: ^5.5.0
+        version: 5.9.3
+      vite:
+        specifier: ^5.3.4
+        version: 5.4.21(@types/node@20.19.41)(lightningcss@1.32.0)
+
   apps/server:
     dependencies:
       '@ai-sdk/openai-compatible':