Add location-wide MCP switches to session options

[eivindjonassen]

Summary

• Keep the current branch visible and add a trailing Location options sheet beside Session and Changes.
• Add native MCP on/off switches scoped to the exact session location, with separate connection, authentication, and failure status.
• Reuse shared switch colors to keep the on-track distinct from the thumb.
• Add generated-client adapter operations, deterministic fixtures, and tests for scope isolation, cancellation, duplicate toggles, uncertain outcomes, and switch contrast.
• Document the accepted experimental runtime operations and preview OTA publications for runtime 0.1.5.

Validation

• pnpm check passed, including 91 adapter tests, 440 mobile tests, and both Hermes exports.
• pnpm native:doctor passed all 18 checks.
• Public-tree and secret scans passed.
• Corrected switch appearance and MCP mutations still need physical-device verification.

Scope

MCP controls affect every session at the same exact location. They do not edit saved configuration and may reset on server restart. Add/remove, mobile OAuth, and resource browsing are not included.