ax: implement monitor dashboard Web UI

[anj-s]

Summary

• Premium Dashboard Frontend: Added a beautiful dark-mode Single Page Application (SPA) in cmd/ax/web/index.html.
• Static Assets Embedding: Configured Go's //go:embed to package the dashboard directly inside the ax CLI binary.
• Trace Visualization Integration: Added an inline interactive execution trace viewer that loads and visualizes historical/active runs dynamically (migrated logic from the standalone ax trace command).
• Auto-Initialization: Enforced database schema initialization in ax monitor to avoid runtime failures on empty databases.
• Environment Automation Script: Created hack/run-ax-environment.sh to boot the python harness server, AX orchestrator (ax serve), and AX monitor dashboard in a single command, handling SIGINT cleanups gracefully.

Type of Change

• New feature (non-breaking change which adds functionality)
• Bug fix
• Refactor
• Documentation
• Breaking change

Related Issues

Part 5 of the Observability & Monitoring epic. Stacked on top of PR #74.

Test Plan

• Automated Tests: Unit tests pass:

  go test -v ./cmd/ax

• Manual Verification: Run the automated environment script, which launches all 3 servers and automatically opens the browser to the dashboard:

  export GEMINI_API_KEY="your-key"
  ./hack/run-ax-environment.sh

Notes for Reviewer

This is the final PR in the Observability & Monitoring epic, completing the rollout of the premium local web dashboard.

[rakyll]

We need to expose OTLP and export telemetry to user's choice of observability tool instead. We shouldn't over build things directly in AX.

[anj-s]

We need to expose OTLP and export telemetry to user's choice of observability tool instead. We shouldn't over build things directly in AX.

what is OTLP? I am only aware of OTEL logs.
This is purely for debugging the controller and conversations that the user is launching via AX. The OTEL telemetry will be streamed from the Harness running on the worker but we need something to understand all the jobs running via AX. This is purely a debugging tool for development. I can add docs and refactor to make that clear.

[rakyll]

Ditto that we should call this dashboard, otherwise LGTM.