fix(kanban): preserve worker tools with restricted toolsets

[haran2001]

Summary

• Ensure dispatcher-spawned kanban workers always include the kanban toolset when HERMES_KANBAN_TASK is set, even if the assignee profile restricts enabled toolsets.
• Keep board-routing tools hidden from task-scoped workers via the existing kanban tool check_fn gates.
• Include the kanban worker mode in the quiet tool-definition cache key so cached schemas do not cross the normal-chat/worker boundary.

Test Plan

• python -m pytest tests/tools/test_kanban_tools.py::test_kanban_worker_env_overrides_profile_toolset_filter -q -o 'addopts='
• python -m pytest tests/tools/test_kanban_tools.py -q -o 'addopts='

Closes #26730

[teknium1]

Merged via PR #28396 (cherry-picked onto current main with your authorship preserved via rebase-merge — commit c30608c). Thanks for the contribution!