feat: add mcp workspace and release flow

[TrueNine]

Summary

• add the new @truenine/memory-sync-mcp workspace package and stdio MCP server scaffold
• expose prompt management APIs from @truenine/memory-sync-cli for MCP reuse
• wire mcp into version sync and npm release workflows
• bump workspace versions to 2026.10318.10339

Validation

• pnpm -F @truenine/memory-sync-mcp run lint
• pnpm -F @truenine/memory-sync-mcp run typecheck
• pnpm -F @truenine/memory-sync-mcp run build
• pnpm -F @truenine/memory-sync-mcp run test
• pnpm exec turbo run build lint typecheck test --filter=@truenine/memory-sync-cli --filter=@truenine/memory-sync-mcp
• pnpm exec tsx .githooks/sync-versions.ts