Extract settings desktop context diagnostics view model

[FanyinLiu]

Summary

• Extract Settings > Memory desktop-context status mapping into a pure diagnostics view model.
• Keep foreground-window, clipboard, and screenshot/OCR diagnostics capability-only, with no new sensing behavior.
• Coarsen platform dependency hints in Settings diagnostics so local environment/tool details are not exposed through the UI model.
• Update the executable optimization task list and changelog without changing package version, tags, README stable release state, or creating any release.

External review

• Asked web ChatGPT Pro to review the actual source code, not just a summary.
• Pro flagged one P0 boundary issue: overly specific platform dependency hints could expose environment fingerprint details.
• Fixed by returning coarse settings.platform.unavailable diagnostics and adding regression coverage that prevents dependency params and specific Linux display/tool names from appearing in diagnostic output.
• Pro re-reviewed the patched source and confirmed the P0 was closed; remaining notes were non-blocking P1 follow-ups.

Verification

• node --experimental-strip-types --test tests/desktop-context-diagnostics.test.ts tests/memory-settings-view.test.ts tests/platform-profile.test.ts
• npx tsc -b --pretty false
• npm run desktop-context-privacy:audit
• npm run architecture:audit
• npm run lint
• npm run companion-boundary:audit
• git diff --check
• npm run v04:draft-stack:audit:quick
• npm run verify:pr