feat: wire mobile app to real Timmy backend via JSON REST API (#73)

Add /api/chat, /api/upload, and /api/chat/history endpoints to the
FastAPI dashboard so the Expo mobile app talks directly to Timmy's
brain (Ollama) instead of a non-existent Node.js server.

Backend:
- New src/dashboard/routes/chat_api.py with 4 endpoints
- Mount /uploads/ for serving chat attachments
- Same context injection and session management as HTMX chat

Mobile app fixes:
- Point API base URL at port 8000 (FastAPI) instead of 3000
- Create lib/_core/theme.ts (was referenced but never created)
- Fix shared/types.ts (remove broken drizzle/errors re-exports)
- Remove broken server/chat.ts and 1,235-line template README
- Clean package.json (remove express, mysql2, drizzle, tRPC deps)
- Remove debug console.log from theme-provider

Tests: 13 new tests covering all API endpoints (all passing).

https://claude.ai/code/session_01XqErDoh2rVsPY8oTj21Lz2

Co-authored-by: Claude <noreply@anthropic.com>

src/dashboard/routes/chat_api.py

@@ -0,0 +1,156 @@
+"""JSON REST API for mobile / external chat clients.
+
+Provides the same Timmy chat experience as the HTMX dashboard but over
+a JSON interface that React Native (or any HTTP client) can consume.
+
+Endpoints:
+    POST /api/chat       — send a message, get Timmy's reply
+    POST /api/upload     — upload a file attachment
+    GET  /api/chat/history  — retrieve recent chat history
+    DELETE /api/chat/history — clear chat history
+"""
+
+import logging
+import os
+import uuid
+from datetime import datetime
+
+from fastapi import APIRouter, File, Request, UploadFile
+from fastapi.responses import JSONResponse
+
+from config import settings
+from dashboard.store import message_log
+from timmy.session import chat as timmy_chat
+
+logger = logging.getLogger(__name__)
+
+router = APIRouter(prefix="/api", tags=["chat-api"])
+
+_UPLOAD_DIR = os.path.join("data", "chat-uploads")
+
+
+# ── POST /api/chat ────────────────────────────────────────────────────────────
+
+@router.post("/chat")
+async def api_chat(request: Request):
+    """Accept a JSON chat payload and return Timmy's reply.
+
+    Request body:
+        {"messages": [{"role": "user"|"assistant", "content": "..."}]}
+
+    Response:
+        {"reply": "...", "timestamp": "HH:MM:SS"}
+    """
+    try:
+        body = await request.json()
+    except Exception:
+        return JSONResponse(status_code=400, content={"error": "Invalid JSON"})
+
+    messages = body.get("messages")
+    if not messages or not isinstance(messages, list):
+        return JSONResponse(status_code=400, content={"error": "messages array is required"})
+
+    # Extract the latest user message text
+    last_user_msg = None
+    for msg in reversed(messages):
+        if msg.get("role") == "user":
+            content = msg.get("content", "")
+            # Handle multimodal content arrays — extract text parts
+            if isinstance(content, list):
+                text_parts = [
+                    p.get("text", "") for p in content
+                    if isinstance(p, dict) and p.get("type") == "text"
+                ]
+                last_user_msg = " ".join(text_parts).strip()
+            else:
+                last_user_msg = str(content).strip()
+            break
+
+    if not last_user_msg:
+        return JSONResponse(status_code=400, content={"error": "No user message found"})
+
+    timestamp = datetime.now().strftime("%H:%M:%S")
+
+    try:
+        # Inject context (same pattern as the HTMX chat handler in agents.py)
+        now = datetime.now()
+        context_prefix = (
+            f"[System: Current date/time is "
+            f"{now.strftime('%A, %B %d, %Y at %I:%M %p')}]\n"
+            f"[System: Mobile client]\n\n"
+        )
+        response_text = timmy_chat(
+            context_prefix + last_user_msg,
+            session_id="mobile",
+        )
+
+        message_log.append(role="user", content=last_user_msg, timestamp=timestamp)
+        message_log.append(role="agent", content=response_text, timestamp=timestamp)
+
+        return {"reply": response_text, "timestamp": timestamp}
+
+    except Exception as exc:
+        error_msg = f"Timmy is offline: {exc}"
+        logger.error("api_chat error: %s", exc)
+        message_log.append(role="user", content=last_user_msg, timestamp=timestamp)
+        message_log.append(role="error", content=error_msg, timestamp=timestamp)
+        return JSONResponse(
+            status_code=503,
+            content={"error": error_msg, "timestamp": timestamp},
+        )
+
+
+# ── POST /api/upload ──────────────────────────────────────────────────────────
+
+@router.post("/upload")
+async def api_upload(file: UploadFile = File(...)):
+    """Accept a file upload and return its URL.
+
+    Response:
+        {"url": "/static/chat-uploads/...", "fileName": "...", "mimeType": "..."}
+    """
+    os.makedirs(_UPLOAD_DIR, exist_ok=True)
+
+    suffix = uuid.uuid4().hex[:12]
+    safe_name = (file.filename or "upload").replace("/", "_").replace("\\", "_")
+    stored_name = f"{suffix}-{safe_name}"
+    file_path = os.path.join(_UPLOAD_DIR, stored_name)
+
+    contents = await file.read()
+    with open(file_path, "wb") as f:
+        f.write(contents)
+
+    # Return a URL the mobile app can reference
+    url = f"/uploads/{stored_name}"
+
+    return {
+        "url": url,
+        "fileName": file.filename or "upload",
+        "mimeType": file.content_type or "application/octet-stream",
+    }
+
+
+# ── GET /api/chat/history ────────────────────────────────────────────────────
+
+@router.get("/chat/history")
+async def api_chat_history():
+    """Return the in-memory chat history as JSON."""
+    return {
+        "messages": [
+            {
+                "role": msg.role,
+                "content": msg.content,
+                "timestamp": msg.timestamp,
+            }
+            for msg in message_log.all()
+        ]
+    }
+
+
+# ── DELETE /api/chat/history ──────────────────────────────────────────────────
+
+@router.delete("/chat/history")
+async def api_clear_history():
+    """Clear the in-memory chat history."""
+    message_log.clear()
+    return {"success": True}