Refactor OVMS architecture for native lifecycle and extensibility

[codex-corp]

What changed

• Unifies server startup around config.json; dynamic config is now the only runtime path.
• Adds settings.json and runtime-manifest.json as explicit sources of truth for local settings and supported OVMS version.
• Pins the current stable OVMS release to 2026.2 and centralizes install/version handling.
• Moves model preparation toward native OVMS lifecycle commands: pull, configure, enable, and disable.
• Removes manual graph.pbtxt generation from the installer/model download flow.
• Keeps switch / rollback compatibility while moving state/log files from the misspelled artficats path to artifacts.
• Refactors the optional IDE proxy into a gateway package with passthrough-by-default adapters.
• Preserves reasoning/tool-call fields by default; legacy stripping is opt-in.
• Replaces global/chunk-as-token telemetry with per-request TTFT and token metrics when real token usage is available.
• Shrinks Python dependencies to the gateway requirement only.
• Adds Python unit tests and a Windows GitHub Actions workflow that also parses PowerShell scripts.
• Updates README/INSTALL/ARCHITECTURE docs to match the new flow.

Scope intentionally deferred

• New model catalog / MoE model shortlist.
• Model-specific memory/offload profiles.
• Hardware benchmark matrix.

Those can be built on top of this architecture once the refactor is reviewed.

Validation

Local checks performed before pushing:

• python -m compileall proxy_server.py tools
• python -m unittest discover -s tests -v (4 tests passing)

The PR CI adds Windows-side PowerShell parsing and repeats Python validation.