feat: add broadcast session tracking and chatlog service with database migrations

videochat/migrations/1_create_broadcast_sessions.up.sql

@@ -0,0 +1,16 @@
+-- 1_create_broadcast_sessions.up.sql
+-- Tabella per registrare ogni apertura e chiusura delle trasmissioni nel servizio videochat.
+
+CREATE TABLE broadcast_sessions (
+    id BIGSERIAL PRIMARY KEY,
+    owner_id TEXT NOT NULL,
+    sid TEXT NOT NULL,
+    name TEXT NOT NULL,
+    action TEXT NOT NULL CHECK (action IN ('OPEN', 'CLOSE')),
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX idx_broadcast_sessions_owner ON broadcast_sessions(owner_id);
+CREATE INDEX idx_broadcast_sessions_sid ON broadcast_sessions(sid);
+CREATE INDEX idx_broadcast_sessions_name ON broadcast_sessions(name);
+CREATE INDEX idx_broadcast_sessions_created_at ON broadcast_sessions(created_at);