feat(agent): add PowerShell command interface

[Avallix]

Summary

Adds PowerShell as a first-class command interface so Windows users can run PowerShell commands through the agent tool loop instead of having PowerShell requests route as unavailable shell/tool actions. The change adds the executor, parser/schema wiring, routing and permission gates, UI labels, and regression coverage for the new tool path.

Target branch

• This PR targets dev, not main. All PRs land in dev; main is curated by the maintainer at each release. If your PR is on main by accident, click "Edit" on this PR and change the base.

Linked Issue

Fixes #6237

Type of Change

• Bug fix (non-breaking — fixes a confirmed issue)
• New feature (non-breaking — adds new behaviour)
• Breaking change (changes or removes existing behaviour)
• Refactor / cleanup (behaviour unchanged)
• Documentation only
• CI / tooling / configuration

Checklist

• I searched open issues and open PRs — this is not a duplicate.
• This PR targets dev
• My changes are limited to the scope described above — no unrelated refactors or whitespace changes mixed in.
• I actually ran the app (docker compose up or uvicorn app:app) and verified the change works end-to-end. Type-checks and unit tests are not enough.
• I did not run the app/runtime validation and stated that gap in How to Test. Leave this unchecked when the app-run box above is checked.

How to Test

1. Start the app from a clean temporary local data directory with auth disabled for validation:

   $env:AUTH_ENABLED='false'
   $env:ODYSSEUS_DATA_DIR = Join-Path $env:TEMP 'odysseus-pr-6238-data'
   $env:APP_PORT='7701'
   .\venv\Scripts\python.exe -m uvicorn app:app --host 127.0.0.1 --port 7701

   The app started successfully at http://127.0.0.1:7701/. ChromaDB-backed RAG/memory reported degraded because ChromaDB was not running locally; the app remained usable and that service is unrelated to this PowerShell command-interface change.

2. Open Settings → Agent Tools, expand the Code section, and verify PowerShell appears with the description Execute PowerShell commands.

3. Run the focused validation used for this branch:

   .\venv\Scripts\python.exe -m py_compile routes\chat_routes.py src\action_intents.py src\agent_loop.py src\agent_tools\__init__.py src\agent_tools\admin_tools.py src\agent_tools\subprocess_tools.py src\task_scheduler.py src\tool_capabilities.py src\tool_index.py src\tool_parsing.py src\tool_policy.py src\tool_schemas.py src\tool_security.py
   .\venv\Scripts\python.exe -m pytest tests\test_action_intents.py tests\test_action_intents_shell_verbs.py tests\test_fenced_inline_args.py tests\test_function_call_non_object_args.py tests\test_live_strip_email_tool_fences.py tests\test_external_context_tool_gate.py tests\test_task_shell_tools.py tests\test_chat_route_tool_policy.py

   Result from the local run: 235 passed, 1 warning.

4. Run the manual PowerShell smoke checks:

   Get-Command i | Select-Object -ExpandProperty Source

   The direct tool smoke resolved i.exe, and the dispatcher smoke returned dispatcher-ok with exit code 0.

Visual / UI changes — REQUIRED if you touched anything that renders

Anything that changes what the UI looks like — buttons, icons, padding, colors, fonts, spacing, layout, CSS, HTML, SVG, or any static/js module that draws to the DOM — needs all of the following. PRs that change rendering without these WILL be closed.

• Screenshot or short clip of the change in the running app, attached below. Mobile screenshot too if the change affects mobile.
• Style match: the change uses Odysseus's existing visual language. Specifically:
  • Reuse existing CSS variables (--red, --fg, --bg, --card, --border, etc.) — do not introduce new color values, font sizes, or spacing units.
  • Reuse existing button/input/card/border classes. Don't invent parallel styling.
  • No Unicode emoji in UI or code. Use inline SVG (matching the monochrome icon style already in static/index.html) or plain text.
  • Monospaced font (Fira Code) for primary UI text. Don't override.
  • Dark theme is the default; any light-mode work must be wired through the existing theme system, not hard-coded.
• No new component patterns. If a similar widget already exists in the app, extend it instead of writing a parallel one.
• I am not an LLM agent submitting a bulk PR. This PR was prepared with an agent, and issue Add PowerShell as a native command interface #6237 was opened first as requested by the contribution guide.

Screenshots / clips