Add version-aware CLI and harness update workflow

Introduce a consistent, version-aware update experience for the N|Solid Plugin across the CLI and all supported harnesses.

• CLI-only updates by default
• Per-harness updates with --harness
• Updates for every detected installation with --all
• Read-only update checks with --check
• JSON and non-interactive automation
• Per-target results and failure isolation
• Credential and user-configuration preservation
• Rollback guidance and transactional Antigravity recovery

Each installation should be updated through its owning mechanism: native Claude and Codex marketplace commands, Antigravity replacement with backup and rollback, the Pi npm package, or fallback reinstallation from the latest published CLI bundle.

Also add release preparation and validation tooling that keeps the core package, Pi package, bundle, and generated manifests on one semantic version. The tooling must detect version drift and ensure user-visible changes increment the release version, without publishing, tagging, committing, or pushing automatically.