fix(WhereUI): guard Settings navigation footprints

[kyleve]

Posted by an AI agent on kve's behalf.

Summary

• add a DEBUG-only heuristic tripwire for oversized concrete content crossing SettingsFocusScope
• render typed Settings destinations through a nominal SettingsRouteView while preserving the production stack's heterogeneous navigation
• exercise every push destination plus nested Evidence and archive routes from one production-shaped app scope
• document nominal child-view extraction as a UI construction defense for agents

Why

The Estimated Time & Planning feature page pushed a large declarative view value over the device stack limit while SwiftUI applied environment values during navigation. The first guard attempt then exposed two problems of its own: its homogeneous [SettingsRoute] test seam prevented child destinations from pushing other value types, and its heuristic size check would have remained an intentional Release crash.

Review focus

• The 56 KiB threshold is deliberately DEBUG-only. It is a deterministic CI tripwire between the measured 46,912-byte survivor and 62,680-byte failure, not a portable ABI guarantee.
• Production keeps an unbound NavigationStack, so Evidence and ShareEvidenceFeaturesView.Route can coexist with SettingsRoute.
• SettingsRouteViewTests owns a heterogeneous NavigationPath, covers every non-sheet destination, and proves both nested route types reach a third navigation level.
• The test fixture derives its model, session, report, backup, and reminders from one loaded scope, matching production ownership.
• Route rendering is a production child view; no test-only SettingsView initializer ships or needs SPI exposure.

Compatibility

No persisted data, user-visible behavior, or Release precondition changes. The child PR is stacked on #252 because that feature page supplied the concrete tree that reproduced the crash.

Testing

• ./swiftformat --lint
• ./test WhereUITests — 432 tests passed
• ./test --only 'WhereUITests/SettingsRouteViewTests' — 3 tests and 14 destination arguments passed without the homogeneous-path warning
• ./test --snapshots — 43 suites passed without recording references
• after merging latest main, WhereFormatTests passed 27 tests and the Calendar/Year snapshot suites both passed

Stack

• 2 of 2; stacked on feat(Where): improve estimated time and planning #252

[kyleve]

Posted by an AI agent on kve's behalf.\n\nThis threshold is intentionally a DEBUG/CI heuristic, not a portable ABI boundary. If a future destination trips it, extract the large declarative subtree behind a nominal child view rather than raising the threshold; Release deliberately has no corresponding precondition.