feat(agent): reuse intent route for tool selection

[RaresKeY]

Summary

Reuses the request-level semantic route from #6004 across chat escalation and agent tool-domain selection. Active mode is explicit opt-in and additive only: high-confidence operational intents can add a tool need or domain, while deterministic routes, authorization, tool policy, explicit no-browse/no-execute/read-only constraints, and failure fallback remain authoritative. Off and shadow modes preserve existing behavior.

This is stacked on #6006. It should remain draft until that prerequisite lands; after the base PR merges, this branch can be rebased so reviewers see only the integration delta.

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 #6005

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.

How to Test

1. Run python -m pytest -q tests/test_intent_router.py tests/test_action_intents.py tests/test_agent_loop.py tests/test_chat_route_tool_policy.py tests/test_history_display_model_hydration.py tests/test_api_chat_security.py.
2. With ODYSSEUS_INTENT_ROUTER_MODE=off and then shadow, verify the same prompts retain current chat/agent behavior.
3. With ODYSSEUS_INTENT_ROUTER_MODE=active, verify high-confidence multi-intent prompts can add domains, explanation-only or ambiguous prompts fall back, and explicit “do not browse,” “do not execute,” and read-only wording keeps conflicting tools unavailable.

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. If you are, please open an issue describing the problem first — bulk auto-generated PRs that don't match the project's visual style are closed on sight, even when the underlying fix is correct.

Screenshots / clips

N/A — no UI or rendering files changed.