feat: Add transcript engine API and connect ConversationHistory to real data

- Add transcript-engine service that parses Claude Code JSONL transcripts
  with session listing, message extraction, token/stats analysis, and caching
- Add transcript REST routes (sessions list, latest, by session ID, section filtering)
- Rewrite ConversationHistory to fetch from /api/transcript/* instead of mock data
- Add session pills for switching between conversation sessions
- Add stats bar footer with model, duration, tokens, and tool count
- Add TranscriptSession/TranscriptMessage types, ChatInput, InputSettings,
  PromptBar updates, TranscriptCard, and useVoiceCapture composable

server/routes/index.ts

@@ -20,6 +20,7 @@ import {
   handleAgentsPlugins, handleAgentsMcpJson,
   handleAgentsConfigPermissions, handleAgentsConfigHooks, handleAgentsConfigMcp
 } from './agents'
+import { handleTranscript, handleTranscriptSessions } from './transcript'
 
 export async function handleRequest(req: Request): Promise<Response> {
   const url = new URL(req.url)
@@ -277,6 +278,20 @@ export async function handleRequest(req: Request): Promise<Response> {
     return handleGitFile(url)
   }
 
+  // Transcript
+  if (path === '/api/transcript/sessions' && req.method === 'GET') {
+    return handleTranscriptSessions()
+  }
+
+  if (path === '/api/transcript/latest' && req.method === 'GET') {
+    return handleTranscript(req, url, 'latest')
+  }
+
+  const transcriptMatch = path.match(/^\/api\/transcript\/([a-f0-9-]+)$/)
+  if (transcriptMatch && req.method === 'GET') {
+    return handleTranscript(req, url, transcriptMatch[1])
+  }
+
   // Agents
   if (path === '/api/agents' && req.method === 'GET') {
     return handleAgents(req)