Image Upload Feature (branch: add-image-upload)

Lets users take a selfie (or pick any image) on mobile and drop it into the chat. Designed to merge cleanly alongside concurrent work on main.

To avoid stepping on another agent working on main, nearly all of the code lives in new files. Edits to existing files are kept intentionally tiny and non-overlapping with the message-rendering path.

api/
  images.ts                         ← Hono sub-app: POST /api/images, GET /api/images/:id
database/
  images.ts                         ← chat_images_v1 table + blob storage helpers
shared/
  image-types.ts                    ← ChatImage type, upload limits (separate from types.ts)
frontend/
  components/CameraButton.tsx       ← Mobile camera button (icon + label)
  hooks/useImageUpload.ts           ← Capture → compress → upload flow

• index.ts — +3 lines: import imagesRoutes, mount with app.route("/", imagesRoutes).
• frontend/components/App.tsx — +1 import, +6 JSX lines: render <CameraButton /> above <MessageInput />. Does not touch MessageList, MessageInput, useMessages, db.ts, types.ts, or index.html.

Rendering mermaid diagram...

1. Capture — a hidden <input type="file" accept="image/*" capture="user"> element opens the front-facing camera on iOS and Android.
2. Compress in-browser — images are downscaled to max 1600px and re-encoded as JPEG at quality 0.82 before upload. Keeps uploads fast on cellular.
3. Upload — POST /api/images with a multipart form. Server validates MIME type, stores bytes in std/blob under chat-images/v1/{id}, stores metadata in a new chat_images_v1 SQLite table.
4. Post to chat — the server then calls the existing insertMessage() to append a text message of the form 📷 /api/images/{id}. This means the image is delivered to every other client through the existing SSE stream — zero changes to the message pipeline.
5. View — GET /api/images/:id streams the bytes back with an immutable cache header.

• capture="user" → front camera on iPhone/Android.
• accept="image/*" → also allows picking from the gallery if the user prefers.
• font-size: 16px on any input (inherited from the app) avoids iOS zoom-on-focus.
• Button is large (min-h-10, rounded pill) for easy thumb-tapping.
• EXIF orientation handled via createImageBitmap({ imageOrientation: 'from-image' }).
• Error state shows as a small inline toast above the button so it doesn't shift the layout.

Currently, images show up in the chat as a text line 📷 /api/images/123. To render them as real <img> tags, MessageList.tsx could be taught to detect this prefix and render accordingly. That change is intentionally not made here so this branch stays orthogonal to any concurrent work on MessageList.

A one-liner enhancement once merged:

// In MessageList.tsx, inside the message map:
const imageMatch = msg.text.match(/^📷\s+(\/api\/images\/\d+)/);
if (imageMatch) {
  return <img src={imageMatch[1]} class="max-w-xs rounded-lg" />;
}

• Bytes: std/blob at chat-images/v1/{id}
• Metadata: SQLite table chat_images_v1 (brand new — no migration of existing tables)
• Limits: 8 MB max upload (enforced on both client post-compression and server). MIME allowlist: jpeg, png, webp, heic, heif. application/octet-stream from iOS camera is normalized to image/jpeg.