Reduce wasted model reviews and add a decoupled live monitor

[SamG-Coder]

Reconstruction jobs spend unnecessary reviewer calls on locally invalid candidates and are difficult to inspect or control while running. This adds candidate preflight before model review, aligns type-recovery prompts with available evidence, and introduces a decoupled local progress monitor.

Changes:

• Reject invalid single-function candidate shapes before spending a model review call, preserving the repair and checkpoint workflow.
• Allow explicit byte offsets when type layouts are unknown instead of requiring invented structs or member names.
• Add re-agent monitor: read-only session/log reporting by default, with explicitly configured worker start/stop and reconnection controls. Worker management is an optional dependency.
• Keep the monitor on loopback, protect control endpoints, and check process identity before reconnecting.

The changes are merged into SamG-Coder/reagent main via fork PRs #1 and #2. This submission preserves the individual feature/fix commits and replaces upstream PRs #13 and #14.

Validation:

• Combined merged tree: 210 tests passed, 9 platform-dependent skips.
• Ruff passed; Mypy passed with the Linux platform target.
• Both fork PRs passed CI lint, packaging, Linux Python 3.10–3.13, Windows Python 3.12, and macOS Python 3.13 checks before merge.
• Monitor tests exercise real disposable worker trees, reconnection, duplicate starts, stale identities, progress accounting, partial writes and HTTP protections.
• Wheel and source distribution builds and packaged monitor CLI/resource smoke checks passed for the monitor feature.

No game paths, binaries, generated source, project-specific runners or run reports are included.