feat(phase2): bulk delete + audit log; update roadmap/parity docs

internal/db/db.go

@@ -284,6 +284,38 @@ CREATE INDEX IF NOT EXISTS idx_embeds_message ON embeds(message_id);
 -- Channel slowmode
 ALTER TABLE channels ADD COLUMN IF NOT EXISTS slowmode_seconds INTEGER NOT NULL DEFAULT 0;
 
+-- Audit log
+CREATE TABLE IF NOT EXISTS audit_log (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	server_id UUID NOT NULL REFERENCES servers(id) ON DELETE CASCADE,
+	user_id UUID REFERENCES users(id) ON DELETE SET NULL,
+	action_type VARCHAR(32) NOT NULL,
+	target_type VARCHAR(32),
+	target_id VARCHAR(64),
+	reason TEXT,
+	changes JSONB,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_audit_log_server_created ON audit_log(server_id, created_at DESC);
+CREATE INDEX IF NOT EXISTS idx_audit_log_action ON audit_log(server_id, action_type);
+
+-- Channel permission overrides
+CREATE TABLE IF NOT EXISTS channel_overrides (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	channel_id UUID NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
+	target_type VARCHAR(8) NOT NULL CHECK (target_type IN ('role', 'user')),
+	target_id UUID NOT NULL,
+	allow_bitflags BIGINT NOT NULL DEFAULT 0,
+	deny_bitflags BIGINT NOT NULL DEFAULT 0,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	UNIQUE (channel_id, target_type, target_id)
+);
+
+CREATE INDEX IF NOT EXISTS idx_channel_overrides_channel ON channel_overrides(channel_id);
+CREATE INDEX IF NOT EXISTS idx_channel_overrides_target ON channel_overrides(channel_id, target_type, target_id);
+
 -- Message full-text search
 ALTER TABLE messages ADD COLUMN IF NOT EXISTS search_vector tsvector;
 CREATE INDEX IF NOT EXISTS idx_messages_search ON messages USING GIN(search_vector);