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/transcript.ts

@@ -0,0 +1,81 @@
+import { jsonResponse, errorResponse } from '../utils/cors'
+import { getTranscriptAnalysis, listSessions } from '../services/transcript-engine'
+import type { TranscriptAnalysis } from '../services/transcript-engine'
+
+export function handleTranscriptSessions(): Response {
+  const sessions = listSessions()
+  return jsonResponse(sessions)
+}
+
+export function handleTranscript(req: Request, url: URL, sessionId: string): Response {
+  if (req.method !== 'GET') return errorResponse('Method not allowed', 405)
+
+  const resolvedId = sessionId === 'latest' ? undefined : sessionId
+  const analysis = getTranscriptAnalysis(resolvedId)
+
+  if (!analysis) {
+    return errorResponse('Transcript not found', 404)
+  }
+
+  // Section filtering
+  const section = url.searchParams.get('section')
+  if (section) {
+    return handleSection(analysis, section)
+  }
+
+  // Full response (exclude thinking by default)
+  const includeThinking = url.searchParams.get('includeThinking') === 'true'
+  if (!includeThinking) {
+    return jsonResponse({
+      ...analysis,
+      messages: analysis.messages.filter(m => !m.isMeta)
+    })
+  }
+
+  return jsonResponse({
+    ...analysis,
+    messages: analysis.messages.filter(m => !m.isMeta)
+  })
+}
+
+function handleSection(analysis: TranscriptAnalysis, section: string): Response {
+  switch (section) {
+    case 'messages':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        messages: analysis.messages.filter(m => !m.isMeta)
+      })
+    case 'tokens':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        tokens: analysis.tokens
+      })
+    case 'tools':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        tools: analysis.tools
+      })
+    case 'stats':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        stats: analysis.stats,
+        model: analysis.model,
+        version: analysis.version,
+        duration: analysis.duration,
+        startTime: analysis.startTime,
+        endTime: analysis.endTime
+      })
+    case 'files':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        filesModified: analysis.filesModified
+      })
+    case 'subagents':
+      return jsonResponse({
+        sessionId: analysis.sessionId,
+        subagents: analysis.subagents
+      })
+    default:
+      return errorResponse(`Unknown section: ${section}. Valid: messages, tokens, tools, stats, files, subagents`, 400)
+  }
+}