Add activity push notifications and registration patches

db/migrations/21_push_notifications.sql

@@ -0,0 +1,26 @@
+CREATE TABLE IF NOT EXISTS notification_preferences (
+    user_id INTEGER PRIMARY KEY REFERENCES users(id) ON DELETE CASCADE,
+    language VARCHAR(2) NOT NULL DEFAULT 'de' CHECK (language IN ('de', 'en')),
+    friend_request BOOLEAN NOT NULL DEFAULT TRUE,
+    direct_message BOOLEAN NOT NULL DEFAULT TRUE,
+    event_invitation BOOLEAN NOT NULL DEFAULT TRUE
+);
+CREATE TABLE IF NOT EXISTS push_notifications (
+    id UUID PRIMARY KEY,
+    device_id BIGINT NOT NULL REFERENCES push_devices(id) ON DELETE CASCADE,
+    session_id INTEGER NOT NULL REFERENCES sessions(id) ON DELETE CASCADE,
+    recipient_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    actor_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    kind VARCHAR(32) NOT NULL CHECK (kind IN ('friend_request', 'direct_message', 'event_invitation')),
+    object_id BIGINT NOT NULL,
+    event_key TEXT NOT NULL,
+    token_hash VARCHAR(64) NOT NULL,
+    state VARCHAR(16) NOT NULL DEFAULT 'pending' CHECK (state IN ('pending', 'sent', 'dropped', 'failed')),
+    attempts SMALLINT NOT NULL DEFAULT 0,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    expires_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP + INTERVAL '1 hour',
+    available_at TIMESTAMPTZ NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    UNIQUE(device_id, event_key)
+);
+CREATE INDEX IF NOT EXISTS idx_push_notifications_pending
+    ON push_notifications(available_at) WHERE state='pending';

db/migrations/22_registration_badges.sql

@@ -0,0 +1,3 @@
+-- Assignment/backfill uses configurable dates in community_badges.reconcile at startup.
+CREATE UNIQUE INDEX IF NOT EXISTS idx_user_badges_registration_cohort
+    ON user_badges(user_id) WHERE badge_code IN ('alpha_tester', 'beta_tester', 'early_bird');