fix: also sync AudioConfig.period/rate before JACK restart

Two-part fix for NAM audio dying after buffer change:

1. NAM block size sync moved BEFORE jack_client.start() so the NAM
   subprocess is reloaded before the process callback fires.

2. AudioConfig.period/rate must be updated BEFORE start_jack() reads
   latency_profile. Otherwise the stale boot-time override period
   stomps on the LATENCY_PROFILES entry set by the POST handler,
   causing JACK to start at the wrong period while NAM is at the
   new period — permanent JACK/NAM block size mismatch.

Both bugs together: user changes buffer, JACK restarts with wrong
period due to stale override, NAM subprocess gets mismatched pipe
bytes, returns DI (direct input) for every subsequent callback.

src/web/server.py

@@ -1491,6 +1491,12 @@ class WebServer:
             # Update LATENCY_PROFILES with custom entry so latency_profile resolves it
             LATENCY_PROFILES[effective_key] = target_profile
 
+            # Sync AudioConfig overrides BEFORE JACK restart so latency_profile
+            # used by start_jack() returns the correct period. Without this, the
+            # stale boot-time self.period override stomps on the LATENCY_PROFILES entry.
+            audio_sys.config.period = target_profile["period"]
+            audio_sys.config.rate = target_profile["rate"]
+
             # ── Kill JACK server FIRST (breaks any client deadlock) ──
             # jack.Client.deactivate() is a synchronous JACK protocol call
             # that blocks until the RT callback thread acknowledges. If the