Add FCM device registration and Gitea bug reporter

db/migrations/20_bug_report_submissions.sql

@@ -0,0 +1,13 @@
+-- Short-lived deduplication/cooldown metadata only, never bug titles or bodies.
+CREATE TABLE IF NOT EXISTS bug_report_submissions (
+    id UUID PRIMARY KEY,
+    user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    state VARCHAR(16) NOT NULL DEFAULT 'new'
+        CHECK (state IN ('new', 'sending', 'success', 'failed', 'unknown')),
+    issue_number INTEGER,
+    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    submitted_at TIMESTAMP,
+    expires_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP + INTERVAL '24 hours'
+);
+CREATE INDEX IF NOT EXISTS idx_bug_report_submissions_user
+    ON bug_report_submissions(user_id, submitted_at);