Fix CI app-suite deadlock: cooperative-pool-blocking thread-safety tests (#1339)

* Exclude perf baselines from parallel CI via --skip; sample hung tests

Every app-suite CI run since the perf baselines landed (#1335) has
timed out at the 15-minute job limit — main has been red for five
consecutive runs. The job logs show the PerformanceBaselineTests
fixtures dispatched into the parallel phase despite the
BITCHAT_SKIP_PERF_BASELINES env guard from #1336, followed by ~11
minutes of silence until the timeout kills swiftpm-testing. The suite
passes locally in seconds with identical flags, so the hang is
specific to the CI toolchain/runners — consistent with the known
XCTest-measure-under-parallel-workers hang the serial step was
created to avoid.

Two changes:
- Exclude the baselines from the parallel phase with --skip at the
  SPM level, which removes them from the worker processes entirely
  instead of relying on the env guard reaching setUpWithError. They
  still run (and gate) in the dedicated serial step.
- Wrap the parallel run in a 10-minute watchdog that samples any
  still-running test processes before killing them, so if anything
  else ever hangs, the run fails fast with thread stacks in the log
  instead of a silent 15-minute timeout.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Arm the test-hang watchdog only for the test execution phase

Codex review: swift test builds before running, so the watchdog timer
included dependency resolution and compilation — a cold-cache coverage
build on a slow runner could be killed before tests ever started.
Build the tests in their own step (bounded by the 15-minute job
timeout like any build) and run the watchdog around swift test
--skip-build, tightened to 5 minutes now that it times only test
execution.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

* Hammer transport thread-safety tests from the dispatch pool, not the cooperative pool

The watchdog added in this PR captured the actual CI hang twice, with
identical stacks both times: NostrTransportTests' 100-task groups park
every Swift Concurrency cooperative thread in a blocking queue.sync
(the pool has one thread per core — 3 on CI runners, 10+ on dev
machines, which is why this never reproduced locally). Blocking the
entire cooperative pool violates the forward-progress contract, and
the runners' dispatch wedges under the resulting asyncAndWait flood —
taking concurrently running tests down with it (the panic-reset test
deadlocked in a serviceQueue barrier that never got scheduled).

Run the same 100 concurrent hammer iterations via
DispatchQueue.concurrentPerform from a single global-queue hop instead:
identical thread-safety coverage, executed on dispatch worker threads
where blocking is legal, zero cooperative threads parked.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

bitchatTests/Services/NostrTransportTests.swift

@@ -310,6 +310,15 @@ struct NostrTransportTests {
         withExtendedLifetime(transport) {}
     }
 
+    // These thread-safety tests must hammer from the dispatch pool
+    // (concurrentPerform), NOT a task group: transport calls block in
+    // queue.sync, and a 100-task group runs them on the Swift Concurrency
+    // cooperative pool — one thread per core, just 3 on CI runners. Parking
+    // every cooperative thread in a blocking sync violates the forward
+    // progress contract and wedged dispatch on the CI runners' macOS,
+    // deadlocking the whole app suite into the 15-minute job timeout
+    // (watchdog stacks: NostrTransport.isPeerReachable syncs holding all
+    // pool threads). Blocking is legal on dispatch worker threads.
     @Test("Concurrent read receipt enqueue does not crash")
     @MainActor
     func concurrentReadReceiptEnqueue() async throws {
@@ -318,9 +327,9 @@ struct NostrTransportTests {
         let transport = NostrTransport(keychain: keychain, idBridge: idBridge)
         let iterations = 100
 
-        await withTaskGroup(of: Void.self) { group in
-            for i in 0..<iterations {
-                group.addTask {
+        await withCheckedContinuation { (continuation: CheckedContinuation<Void, Never>) in
+            DispatchQueue.global().async {
+                DispatchQueue.concurrentPerform(iterations: iterations) { i in
                     let receipt = ReadReceipt(
                         originalMessageID: UUID().uuidString,
                         readerID: PeerID(str: String(format: "%016x", i)),
@@ -329,8 +338,10 @@ struct NostrTransportTests {
                     let peerID = PeerID(str: String(format: "%016x", i))
                     transport.sendReadReceipt(receipt, to: peerID)
                 }
+                continuation.resume()
             }
         }
+        withExtendedLifetime(transport) {}
     }
 
     @Test("isPeerReachable is thread safe")
@@ -341,18 +352,16 @@ struct NostrTransportTests {
         let transport = NostrTransport(keychain: keychain, idBridge: idBridge)
         let iterations = 100
 
-        await withTaskGroup(of: Bool.self) { group in
-            for i in 0..<iterations {
-                group.addTask {
+        await withCheckedContinuation { (continuation: CheckedContinuation<Void, Never>) in
+            DispatchQueue.global().async {
+                DispatchQueue.concurrentPerform(iterations: iterations) { i in
                     let peerID = PeerID(str: String(format: "%016x", i))
-                    return transport.isPeerReachable(peerID)
+                    #expect(transport.isPeerReachable(peerID) == false)
                 }
-            }
-
-            for await result in group {
-                #expect(result == false)
+                continuation.resume()
             }
         }
+        withExtendedLifetime(transport) {}
     }
 
     @MainActor