fix: register-retry on cellular failure + aggressive blank-NC sweep

[DocNR]

Summary

Two real bugs surfaced during build 26 testing today:

1. `registerWithProxy` silently drops failures on bad cellular

User launched Clave on weak cellular signal; the auto-register HTTP POST (10s timeout) failed, the failure was silently dropped because the auto-register call sites in `AppState.init` (`.apnsDeviceTokenAvailable` observer) and `loadState()` pass `completion: nil`. Token never reached proxy. Symptom: signing silently failed until user moved to wifi and tapped Settings → Register manually (the manual path surfaces the failure to the UI).

PR #15 was correct on the happy path but didn't self-heal when the initial POST failed.

2. Blank NC entries weren't being swept

PR #13 shipped `MainTabView.sweepBlankNotifications()` filtering on `title.isEmpty`. But the proxy's APNs payload sets `alert: { title: " ", body: " " }` (single SPACE characters, so NSE has something to override). When NSE doesn't run (cold-launch race, timeout, force-quit recovery), iOS keeps the proxy's original payload — title is " " (single space), NOT empty. Sweep never matched these. User reported 8 blank entries accumulating in NC while Clave was backgrounded for ~30 min during a session.

Changes

• New `Clave/Views/Components/NotificationCenterSweep.swift`: extracts `sweepBlankNotifications()` to a top-level free function so both `MainTabView` and `ForegroundRelaySubscription` can call it. Filter now trims whitespace and checks BOTH title AND body, catching the proxy single-space fallback.

• `MainTabView.handleScenePhase`: sweeps on `.inactive` too (catches user opening NC via swipe-down while Clave is most-recent foreground app but not `.active`). Also calls `appState.ensureRegisteredFresh()` on `.active`.

• `Shared/ForegroundRelaySubscription.swift`: calls `sweepBlankNotifications()` after each in-process event. Catches the case where Clave is foregrounded and a parallel APNs push leaves a blank NC entry from NSE's `.noEvents` return.

• `Clave/AppState.swift`:

  • `registerWithProxy()` records `lastRegisterSucceededAtKey` / `lastRegisterFailedAtKey` timestamps in app-group defaults.
  • New `ensureRegisteredFresh()` gates re-registers: skips if last success < 30 min ago, applies 60s cooldown after failures so a dead proxy doesn't get hammered on every foreground.

• `Shared/SharedConstants.swift`: adds the two new defaults keys.

Test plan

• `xcodebuild build` → BUILD SUCCEEDED
• `xcodebuild test` → TEST SUCCEEDED
• Device test (build 27):
  • On bad cellular: launch Clave, observe registration fails silently. Move to wifi, foreground Clave. Verify `ensureRegisteredFresh()` retries — check proxy log for `[HTTP] Registered` line.
  • Open NC after ~10 min of Clave backgrounded with active signing happening. Should be empty (sweep ran on .inactive transitions).
  • If blanks DO show up briefly, opening Clave once should clear them (sweep on .active).
  • Hot-loop guard: with proxy unreachable, background/foreground 5x in 60 sec. Verify only 1 register attempt fires (60s failure cooldown).

Closes

BACKLOG: "registerWithProxy() retry on transient network failure" (opened earlier today, fixed same day).

🤖 Generated with Claude Code