fix(workstation): hide tools the requester lacks view_tool on (IKABQ0)

[yaojin3616]

Summary

The end-user workspace chat toolbar (GET /api/v1/workstation/config) was
returning every tool the admin had configured for daily chat, with no
intersection against the caller's view_tool / use_tool permission. Any
logged-in end user could therefore see the full set of API and MCP tools
the admin had pinned for the daily-chat agent, regardless of whether
they had been granted access. This was a leak of the admin workbench
surface into the end-user chat surface.

Root cause

WorkStationService.aget_config() /
get_daily_chat_config() / get_linsight_config() returned the
admin-configured WorkstationConfig.tools list verbatim, with no
per-user permission intersection. The platform tool list path
(tool.domain.services.tool.ToolServices.get_tool_list) already does
this via ToolPermissionService.filter_tool_ids_by_permission_async
when listing tools in the admin UI; the workstation path did not.

Fix

• Add WorkStationService._afilter_tools_by_view_permission, which pipes
  the projected tool list through
  ToolPermissionService.filter_tool_ids_by_permission_async(user_id, ids, "view_tool") before returning.
• Wire login_user through the public service methods
  (aget_config, get_daily_chat_config,
  get_daily_chat_config_with_meta, get_linsight_config,
  get_linsight_config_with_meta) and their internal projection
  helpers. Update endpoint handlers (/config, /config/daily,
  /config/linsight, /app/recommended) and the chat service to pass
  the caller's login_user.
• Filter is fail-closed on permission-probe errors (no leak), bypassed
  for admins (config page still echoes every configured tool), and a
  no-op when login_user is None (legacy/test paths keep prior
  behaviour).

Files

• src/backend/bisheng/workstation/domain/services/workstation_service.py
  — add helper, propagate login_user, apply filter in both inherited
  and non-inherited branches.
• src/backend/bisheng/workstation/api/endpoints/config.py — pass
  login_user to the three public service methods.
• src/backend/bisheng/workstation/api/endpoints/apps.py — pass
  login_user to aget_config.
• src/backend/bisheng/workstation/domain/services/chat_service.py —
  pass login_user to the two aget_config callers.
• src/backend/test/workstation/test_workstation_tool_permission_filter.py
  — regression coverage: non-admin-without-permission, admin bypass,
  no-login-user, fail-closed, empty list, and missing-id cases.

Test plan

• New regression test in
  test/workstation/test_workstation_tool_permission_filter.py covers
  the helper's six behavioural branches.
• Existing test/workstation/* suite to confirm no regressions
  (all callers updated, the new login_user parameter is keyword-only
  with a default of None so mocks that don't pass it still work).
• Manual: log in as a non-admin user without view_tool on a
  configured API/MCP tool, open the chat workspace, confirm the tool
  no longer appears in the agent tool selector. Re-test as an admin
  and confirm the tool is still visible.

Risk

Low. The change is additive (a new login_user keyword argument on
the public methods) and the filter is bypassed when no user is passed
so existing tests / legacy call paths that don't yet pass login_user
keep their prior behaviour.

Closes IKABQ0.