fix: rebalance switcher focus insets

[sonim1]

Summary

• Rebalance the application switcher so its 96 pt icon keeps its size while the blue focus treatment shrinks to 94 pt and the caption gains a scaled bottom inset.
• Increase window-switcher content insets to 6 pt on every edge around the title and thumbnail.
• Keep application panel height and grid-cell width stable, including minimum and maximum overlay-size settings.
• Document the final geometry contract and the reasoning behind the focus-inset split.

Test Coverage

CODE PATHS                                      USER FLOWS
[+] Layout policy (5/5 covered)                 [+] Runtime switching (0/2 automated)
  ├── [★★★ TESTED] Window 6pt H/V insets          ├── [MANUAL PASS] Cmd-` visual padding
  ├── [★★ TESTED] Window inset scaling             └── [MANUAL PASS] Cmd-Tab focus/caption spacing
  ├── [★★★ TESTED] App 100/96/94pt separation
  ├── [★★★ TESTED] App bottom inset at min/default/max
  └── [★★ TESTED] Compact layout/bounds remain stable
[+] SwiftUI wiring (3/3 covered)
  ├── [★ TESTED] Window directional modifiers
  ├── [★★ TESTED] 94pt focus frame precedes outer 96pt frame
  └── [★★★ TESTED] Caption/panel height remains independent

COVERAGE: 8/10 automated paths (80%) | Code: 8/8 (100%) | User flows: 2/2 manually approved

Coverage gate: PASS at the 80% target. The two native-macOS visual flows were verified in the signed local Debug app and approved before release.

Pre-Landing Review

Clean. Review found two medium layout-test issues; both were fixed and the final re-review returned APPROVE with no blockers.

Design Review

Manual visual QA passed for both application and current-app window switchers using the signed local Debug build.

Eval Results

No prompt-related files changed; evals skipped.

Scope Drift

Scope Check: CLEAN. The diff is limited to switcher focus geometry, its tests, and the matching design/implementation documentation.

Plan Completion

All 8 plan items are complete. Final approved values are aligned across code, tests, and docs; no items are deferred or unverifiable.

Verification Results

• Swift tests: 19 tests, 0 failures
• Release contract tests: 13 scripts passed
• Unsigned arm64 Xcode Debug build: succeeded
• git diff --check: clean
• Local signed Debug visual verification: passed

Documentation

• Audited all live project documentation and the feature design/implementation plan against the overlay-padding diff.
• No documentation updates were required: the final 94 pt application selection extent, scaled 4 pt default bottom inset, and 6 pt window content inset are documented.
• No public command, configuration, permission, release workflow, or architecture diagram changed.

Test plan

• Application switcher focus treatment and caption spacing verified locally
• Current-app window switcher focus padding verified locally
• Swift suite passes
• Release contract suite passes
• Unsigned Xcode build succeeds