feat: add web push notifications and file drop

Web Push:
- WebPushNotifier with VAPID auth; urgency mapped to event type
  (BLOCKED=urgent, FAILED=high, COMPLETED=low)
- Auto-generates VAPID keys on first serve, persists to config file
- push_subscriptions table in SQLite (upsert by endpoint)
- GET /api/push/vapid-key, POST/DELETE /api/push/subscribe endpoints
- Service worker (sw.js) handles push events and notification clicks
- Notification bell button in web UI; subscribes on click

File Drop:
- GET /api/drops, GET /api/drops/{filename}, POST /api/drops
- Persistent ~/.claudomator/drops/ directory
- CLAUDOMATOR_DROP_DIR env var passed to agent subprocesses
- Drops tab (📁) in web UI with file listing and download links

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/internal/notify/vapid.go b/internal/notify/vapid.go
new file mode 100644
index 0000000..90d535b
--- /dev/null
+++ b/internal/notify/vapid.go
@@ -0,0 +1,9 @@
+package notify
+
+import webpush "github.com/SherClockHolmes/webpush-go"
+
+// GenerateVAPIDKeys generates a VAPID key pair for web push notifications.
+// Returns the base64url-encoded public and private keys.
+func GenerateVAPIDKeys() (publicKey, privateKey string, err error) {
+	return webpush.GenerateVAPIDKeys()
+}