client/models/server: wire event_count from SUB 08 event index into connect()

- DeviceInfo.event_count: Optional[int] = None  (new field in models.py)
- connect() now calls proto.read_event_index() after compliance config and
  stores the decoded count in device_info.event_count
- _serialise_device_info() exposes event_count in /device/info and /device/events
  JSON responses

event_count is decoded from uint32 BE at offset +3 of the 88-byte F7 payload
(🔶 inferred — needs live device confirmation against a multi-event device).
Any ProtocolError from the index read is caught and logged; event_count stays
None rather than failing the whole connect().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

minimateplus/models.py

@@ -183,6 +183,9 @@ class DeviceInfo:
     # ── From SUB 1A (COMPLIANCE_CONFIG_RESPONSE) ──────────────────────────────
     compliance_config: Optional["ComplianceConfig"] = None  # E5 response, read in connect()
 
+    # ── From SUB 08 (EVENT_INDEX_RESPONSE) ────────────────────────────────────
+    event_count: Optional[int] = None  # stored event count from F7 response 🔶
+
     def __str__(self) -> str:
         fw = self.firmware_version or f"?.{self.firmware_minor}"
         mdl = self.model or "MiniMate Plus"