refactor(mcp-bridge): raise AAA description + schema floor

Follow-up audit after the initial AAA uplift found three weakness classes
pulling down the 40% MIN component of Glama's TDQS:

* 5 tools in the 80-100 char band (boj_ml_huggingface=80, coord_status=81,
  coord_review_entry=87, boj_cloud_verpex=90, coord_approve=93)
* 20 tools missing `additionalProperties: false`
* 2 GitHub/GitLab one-liners just under 120 chars

Expanded every thin description to >=120 chars with full purpose / usage /
side-effect / return / error content. Added `additionalProperties: false`
to all 65 schemas so unknown keys are rejected. Tightened the dispatch
test suite accordingly:

* floor raised 80 -> 120 chars
* new mean-length test (>=200 chars)
* new closed-schema test (all schemas must be `additionalProperties:false`)

Final metrics: 65 tools, description min=123, mean=336, max=630; 65/65
schemas closed; all 8 dispatch tests green.

https://claude.ai/code/session_01AQeaZPrDneQqFYxwxVTJqm

Author: claude