Add a decoupled live progress monitor with worker controls

[SamG-Coder]

Long-running reconstruction jobs are difficult to inspect and control from terminal logs alone. This adds re-agent monitor, a decoupled local dashboard that reads existing session files and activity logs without starting model work.

The dashboard shows unique saved function results, review passes, failures, repair rounds, and recent activity. It is read-only by default. An explicitly configured worker argv enables start/stop controls and reconnection after a host restart; closing the browser or host leaves the worker running. The optional monitor dependency supplies process management.

Control requests are restricted to loopback, checked Host/Origin headers and a per-host token. HTTP clients cannot choose commands or filesystem paths. Process identity checks and a file lock prevent stale-PID adoption and duplicate starts of the same configured worker. The UI labels review results without claiming binary equivalence.

Validation:

• 204 tests passed, 9 platform-dependent skips.
• 14 monitor tests cover counting/deduplication, partial writes, bounded logs, real worker-tree stopping, duplicate starts, reconnection, stale identities, HTTP controls, and CLI argument handling.
• Ruff passed; Mypy passed with the Linux platform target across 74 source files.
• Wheel and source distribution built successfully; packaged dashboard resource and isolated monitor CLI smoke checks passed.

Includes generic code, tests and documentation only. No game paths, project-specific runners, generated source, or run reports. Based on current upstream main.