Add support for many providers & AI Verdict Engine

[stanfrbd]

Summary

• What does this PR change?
• Why is this change needed?

Scope

• Bug fix
• New feature
• Refactor
• Documentation
• New engine
• Other (describe):

Validation (required)

• I ran relevant tests locally and they pass.
• I validated real behavior (not only code style or static checks).
• I checked edge cases and failure paths.

Test evidence

List exact commands you ran and the outcome.

# Example
pytest -q

AI-assisted contribution disclosure

• This PR includes AI-assisted work.
• I reviewed and understood all generated code.
• I refined AI output where needed (no low-quality slop).
• I am fully responsible for this submission.

If AI was used, briefly describe what parts were AI-assisted:

Maintainer merge policy acknowledgement

• I understand uncertain changes may be merged to dev first for additional validation.
• I understand main is kept clean/stable for releases and tags.

New engine checklist (only if applicable)

Engine Implementation

• Added engine file in engines/engine_name.py (using existing engines as template).
• Added engine import/registration in engines/__init__.py.
• Added engine config/secret variable in utils/config.py (if relevant).

Configuration & Secrets

• Added needed API key/config vars to .env.sample.
• Verified variable templating in docker-compose.yml.

UI & Frontend

• Engine result is copyable via GUI in static/format_results.js.
• Added/updated layouts in templates/engines_layouts/ for card/table rendering.
• Added engine in templates/display_cards.html and templates/display_table.html.
• Added engine in templates/index.html with description (alphabetic order).
• Added engine support for graph view in templates/graph.html.

Documentation

• Added docs in docs/api-keys/Get-Engine-API-key.md (if relevant).
• Added API key guide link in docs/index.md (if relevant).
• Added engine to docs/quick-start/API-usage-and-engine-names.md.
• Added page in mkdocs.yml sidebar.
• Updated docs/quick-start/Quick-start-&-Installation.md and .env examples.
• Added env vars to docs/quick-start/Advanced-options-for-deployment.md (docker compose example).
• Updated README.md references (env vars and API/services section).

Risk and rollback

• Risk level: Low / Medium / High
• Potential impact:
• Rollback strategy:

Additional notes

• Any reviewer context, trade-offs, or follow-up tasks.