feat: add campaign templates and recurring schedules

src/GmRelay.Bot/Migrations/V010__add_campaign_templates.sql

@@ -0,0 +1,17 @@
+CREATE TABLE campaign_templates (
+    id                  UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    group_id            UUID NOT NULL REFERENCES game_groups(id) ON DELETE CASCADE,
+    name                VARCHAR(200) NOT NULL,
+    title               VARCHAR(500) NOT NULL,
+    join_link           TEXT NOT NULL,
+    session_count       INTEGER NOT NULL CHECK (session_count BETWEEN 1 AND 52),
+    interval_days       INTEGER NOT NULL CHECK (interval_days BETWEEN 1 AND 365),
+    max_players         INTEGER CHECK (max_players IS NULL OR max_players > 0),
+    notification_mode   VARCHAR(32) NOT NULL DEFAULT 'GroupAndDirect'
+                        CHECK (notification_mode IN ('GroupAndDirect', 'GroupOnly')),
+    created_at          TIMESTAMPTZ NOT NULL DEFAULT now(),
+    updated_at          TIMESTAMPTZ NOT NULL DEFAULT now(),
+    UNIQUE (group_id, name)
+);
+
+CREATE INDEX ix_campaign_templates_group ON campaign_templates (group_id, created_at DESC);