feat: add Google Maps route tools - #137

What

Add optional, read-only Google Maps Routes tools for fresh distance, ETA,
traffic-delay, alternate-route, and scenario-comparison requests.

Why

Blacki needs a lightweight cloud-first route provider before it can support
saved commutes and scheduled traffic summaries. The integration keeps provider
responses ephemeral and protects exact locations and place IDs from logs and
telemetry.

How

• Add a shared async Compute Routes client with bounded retries and stable errors.
• Normalize travel modes, traffic settings, alternatives, warnings, and attribution.
• Route travel requests to dedicated tools instead of generic search.
• Redact route data from logs, tool notifications, and OpenInference spans.
• Wire a dedicated Routes API key through the production deployment workflow.
• Add operator documentation and deterministic ADK route eval cases.

Tests

• uv run ruff format --check
• uv run ruff check
• uv run mypy .
• uv run pytest --cov=src --cov-report=xml --cov-report=term-missing
• 1,200 tests pass with 100% line and branch coverage
• uv run --no-sync mkdocs build --strict
• Run the prepared ADK route eval after explicit approval for model-provider data transfer

Related Issues

Prerequisite for #135.