M1 step 4b: IRC Service on the device; 8-bit frame buffer

- IrcService: networking on its own task, TLS with the built-in CA
  bundle (or trust-on-first-use pinning when self-signed is allowed),
  plain TCP when TLS is off; connects only while Wi-Fi is Connected,
  marks pauses for Monitoring, reconnects with backoff, pings a quiet
  server, writes Logs, raises Notifications for Mentions
- Session: forget /quit once disconnected (it was handled every loop);
  the server Buffer never counts as unread (MOTD showed as [4])
- Status Bar: unread count
- Frame buffer 16 -> 8-bit colour (M1 Q46): min free heap with IRC on
  TLS went from 51 KB to 79 KB
- Serial: irc start / say / dump

Verified on the device against irc.libera.chat:6697: certificate
checked, joined #roro9stack-test, sent a message, quit cleanly.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

src/services/clock_service.h

@@ -23,6 +23,9 @@ class ClockService : public Service {
     bool set(int64_t utcSeconds, TimeSource source) { return model_.set(utcSeconds, source, millis()); }
     const ClockModel& model() const { return model_; }
 
+    // UTC seconds, or -1 if the clock isn't set.
+    int64_t utcNow() const { return model_.isSet() ? model_.utcNow(millis()) : -1; }
+
     // Local "YYYY-MM-DD" once set; otherwise empty (Logs then go to undated files).
     std::string localDate() const { return model_.isSet() ? ClockModel::formatLocalDate(model_.utcNow(millis())) : ""; }
     // Days since 1970-01-01 (UTC), or -1 if the clock isn't set.