Replace permissive JSON Schema Draft-07 whitelist with strict
Gemini-compatible field set (22 fields). The "examples" field
in Claude Code tool schemas caused 400 errors from Gemini API.
Also strips other unsupported fields: $ref, $defs, oneOf, allOf,
additionalProperties, const, if/then/else, etc.
Safe change — sanitizer only runs for CLIProxy profiles (Gemini,
Codex, Antigravity), never for direct Anthropic API requests.
Closes#155