Fix/model error antigravity

[JamesDAdams]

Summary

Fixes tool parameter schema serialization errors (HTTP 400 Invalid value at 'request.tools[0].function_declarations[...].parameters.properties[...].value' (type.googleapis.com/google.cloud.aiplatform.master.Schema), "object") encountered with Google Cloud Vertex AI, Antigravity, and Gemini models:

• Tool Schema Sanitizer (src/server/llm/schema-sanitizer.ts):
  • Recursively strips unsupported keywords across providers (additionalProperties, $schema, $id, patternProperties, etc.).
  • Strips null/undefined fields (e.g. default: null generated by MCP servers such as Jira).
  • Automatically aliases tool parameters named "properties" to "props" in the schema (and remaps them on execution) to prevent collisions with the Protobuf Schema.properties field in Google APIs.
  • Ensures every type: "object" has a defined properties: {} map and every type: "array" has a typed items schema.
• Tool Adapter & Client Hooking:
  • Integrated sanitizeToolSchema across standard LLM client conversion (client-pure.ts), transport adapters (transport-client.ts), and MCP server tool registration (tool-adapter.ts, manager.ts).
• Built-in Tool Definitions:
  • Fixed ask_user options union and project_tasks attachments items schemas to conform to strict provider requirements.

AI-Enhanced Development

Tell what models helped shape this PR:

• AI Models: Gemini 3.7 Flash

Cache Impact

Does this PR affect anything cached — system prompts, tool definitions, skills, or other context?

• Yes
  • Tool definition parameter schemas for built-in tools (ask_user, project_tasks) and MCP tools are now normalized and sanitized (stripping additionalProperties, null defaults, and renaming "properties" parameter to "props"), which updates the cached tool definitions hash.

[co-l]

Merged, will be released in v2.0.136

AI-summary

• Reviewed the schema sanitizer and fixed a bug in the MCP execution remap: when a properties parameter is renamed to props in the LLM-facing schema, the remap left a stray props argument on the call to the MCP server (strict servers would reject it). Added a regression test covering the rename → remap round-trip
• Rebased the PR onto latest develop (3 commits, no conflicts), fixed a Prettier formatting issue in schema-sanitizer.ts
• Verified the full unit suite (5120 passed), typecheck, lint, format and duplicate clean, plus provider e2e green
• Pushed the branch to the contributor's fork so the PR merges cleanly
• Squash-merged