fix(mcp): inject default namespace for memwal_remember_bulk calls

[ducnmm]

Resolves #625 (and companion #611)

Summary

Includes memwal_remember_bulk in the set of NAMESPACE_TOOLS so the configured default namespace (--namespace / MEMWAL_NAMESPACE) is injected when an agent calls bulk remember without an explicit namespace.

Problem

Previously, NAMESPACE_TOOLS in packages/mcp/src/bridge.ts only included memwal_remember, memwal_recall, memwal_analyze, and memwal_restore. When an agent invoked memwal_remember_bulk without an explicit namespace, no namespace argument was injected and the batch was written into the relayer's fallback default namespace, making it unrecallable from the configured project namespace.

Changes

• Added "memwal_remember_bulk" to NAMESPACE_TOOLS in packages/mcp/src/bridge.ts.
• Added unit tests in packages/mcp/test/default-namespace.test.mjs to verify default namespace injection behavior for memwal_remember_bulk and other tools.

Verification

• pnpm --filter @mysten-incubation/memwal-mcp test (14/14 tests pass)