feat(core): support MCP resources - #35656

Summary

• add canonical MCP resource, template, catalog, and text/blob content contracts
• implement paginated resource/template discovery, lazy cached catalogs, uncached reads, and list-change invalidation in V2 Core
• add scoped URI subscriptions with shared server subscriptions, cleanup, callback isolation, and Streamable HTTP session recovery
• publish internal mcp.resources.changed events for catalog and connection transitions

This is the first PR in the MCP resource stack. Protocol/server endpoints, generated clients, frontend autocomplete/materialization, and MCP resource tools are intentionally excluded.

Testing

• bun test --only-failures in packages/schema (28 passed)
• bun typecheck in packages/schema
• bun test --only-failures in packages/core (1,215 passed, 6 skipped)
• bun typecheck in packages/core
• workspace bun typecheck (31 packages)
• git diff --check