feat(core): FK for user_id columns; MCP search requires user

- Add fk_entries_user_id, fk_entries_history_user_id, fk_audit_log_user_id (ON DELETE SET NULL)
- Add scripts/cleanup-orphan-user-ids.sql for pre-deploy orphan user_id cleanup
- Remove deprecated SERVER_MASTER_KEY / per-user key wrap helpers from secrets-core
- secrets-mcp: require authenticated user for secrets_search; improve body-read failure response
- Bump secrets-mcp to 0.2.1

Made-with: Cursor

crates/secrets-core/src/db.rs

@@ -156,6 +156,37 @@ pub async fn migrate(pool: &PgPool) -> Result<()> {
         CREATE INDEX IF NOT EXISTS idx_oauth_accounts_user ON oauth_accounts(user_id);
         CREATE UNIQUE INDEX IF NOT EXISTS idx_oauth_accounts_user_provider
             ON oauth_accounts(user_id, provider);
+
+        -- FK: user_id columns -> users(id) (nullable = legacy rows; ON DELETE SET NULL)
+        DO $$ BEGIN
+            IF NOT EXISTS (
+                SELECT 1 FROM pg_constraint WHERE conname = 'fk_entries_user_id'
+            ) THEN
+                ALTER TABLE entries
+                    ADD CONSTRAINT fk_entries_user_id
+                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
+            END IF;
+        END $$;
+
+        DO $$ BEGIN
+            IF NOT EXISTS (
+                SELECT 1 FROM pg_constraint WHERE conname = 'fk_entries_history_user_id'
+            ) THEN
+                ALTER TABLE entries_history
+                    ADD CONSTRAINT fk_entries_history_user_id
+                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
+            END IF;
+        END $$;
+
+        DO $$ BEGIN
+            IF NOT EXISTS (
+                SELECT 1 FROM pg_constraint WHERE conname = 'fk_audit_log_user_id'
+            ) THEN
+                ALTER TABLE audit_log
+                    ADD CONSTRAINT fk_audit_log_user_id
+                    FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE SET NULL;
+            END IF;
+        END $$;
         "#,
     )
     .execute(pool)