reliability + security fix sprint (vc=91)

Straw full-audit fix batch (2026-07-04). Confirmed HIGH/MED findings:

- Updater self-brick: drop the fdroid.sulkta.com leaf+E7 SPKI pins (LE
  rotates the leaf every ~90d + intermediates from a pool → a routine
  renewal was guaranteed to miss both pins and silently kill the only
  in-app update path). System-CA validation + the install-time APK
  signature gate remain. Also distinguish "index unreachable" from "up to
  date", add a 30s callTimeout + bounded index read, guard the API-26
  NotificationChannel, and setOnlyAlertOnce.
- Request POST_NOTIFICATIONS at runtime so A13+ update/media notifications
  actually post (was declared but never requested → silent no-op).
- isDebuggable=false on the shipped debug variant (closes ADB run-as dump
  of watch/search history + subs; no package-id cutover).
- Crash fixes: distinctBy(url) on moreFromChannel + related (duplicate
  LazyColumn key); back-handling driven by live nav depth so it survives
  moveTaskToBack on A12+; PlaylistsStore per-store caps + off-main
  hydration (hostile import ANR); SponsorBlock staleness fence via
  NowPlaying.refreshIfCurrent.
- CacheCap.nearest() snaps up to the nearest finite cap (defaults no longer
  resolve to Unlimited/100k on fresh installs).
- RYD/SB FFI shims wrap the uniffi call (swallow a core panic per contract).
- Rust wrapper: release panic="unwind" (was "abort", which defeated UniFFI
  catch_unwind → any core panic = whole-app SIGABRT) + a 60s wall-clock
  timeout on every blocking extractor call (unblocks the caller, bounds
  thread pileup). Pairs with the strawcore-core reliability fix.

rust/Cargo.toml

@@ -21,7 +21,14 @@ repository = "https://git.sulkta.com/Sulkta-OSS/straw"
 strip = true
 lto = "thin"
 codegen-units = 1
-panic = "abort"
+# unwind (NOT abort): panic=abort defeats UniFFI's catch_unwind AND tokio's
+# spawn_blocking JoinError capture, turning ANY panic in the extractor core
+# (which chews weekly-rotating, attacker-influenced YouTube payloads) into an
+# instant whole-app SIGABRT. unwind restores both safety nets so a core panic
+# surfaces as a caught StrawcoreException instead of crashing the app. The
+# unwind-table size cost is a rounding error against the 4-ABI jniLibs payload.
+# (straw + FFI-wrapper audits, 2026-07-04.)
+panic = "unwind"
 opt-level = "z"
 
 # `url` crate for video-id extraction in stream.rs.