chore: auto-commit (23 archivos)

- app.md
- backend/auth.go
- backend/db.go
- backend/dist/assets/index-CPqSy0gZ.js
- backend/dist/index.html
- backend/handlers.go
- backend/main.go
- frontend/src/App.tsx
- frontend/src/api.ts
- frontend/src/components/KanbanCard.tsx
- ...

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

backend/migrations/010_card_messages.sql

@@ -0,0 +1,14 @@
+-- Per-card chat messages (human-to-human comments).
+-- Distinct from card_events (which records system events like title_changed)
+-- and from /api/chat (which is the board-level LLM chat).
+
+CREATE TABLE IF NOT EXISTS card_messages (
+    id          TEXT PRIMARY KEY,
+    card_id     TEXT NOT NULL,
+    author_id   TEXT,
+    body        TEXT NOT NULL,
+    created_at  TEXT NOT NULL,
+    FOREIGN KEY (card_id) REFERENCES cards(id) ON DELETE CASCADE
+);
+
+CREATE INDEX IF NOT EXISTS idx_card_messages_card ON card_messages(card_id, created_at);