Fix field name mismatches, add events filter, in-place suppression refresh

- links.html: fix all field name bugs (auto_negotiation→autoneg, full_duplex,
  tx/rx_errors/drops_per_sec→_rate, tx/rx_bytes_per_sec→_rate, poe_total_w/poe_max_w
  computed from ports, renderUnifiSwitches uses top-level updated timestamp)
- suppressions.html: in-place DOM refresh after create/remove (no page reload),
  datalist autocomplete for target names, form reset after submit
- inspector.html: ESC key closes detail panel via lt.keys.on
- index.html: events filter bar with search input + severity pills (All/Critical/Warning),
  MutationObserver re-applies filter after dynamic updates
- style.css: g-section-actions, events-filter-bar, sev-pills layout
- app.js/db.py/monitor.py: carry forward prior session fixes (Promise.allSettled,
  daemon_ok, stale connection handling, double Prometheus call, self.cfg fix)

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

db.py

@@ -23,26 +23,39 @@ def _config() -> dict:
     return _config_cache
 
 
+def _new_conn(cfg: dict):
+    return pymysql.connect(
+        host=cfg['host'],
+        port=cfg.get('port', 3306),
+        user=cfg['user'],
+        password=cfg['password'],
+        database=cfg['name'],
+        autocommit=True,
+        cursorclass=pymysql.cursors.DictCursor,
+        connect_timeout=10,
+        charset='utf8mb4',
+    )
+
+
 @contextmanager
 def get_conn():
     """Yield a per-thread cached database connection, reconnecting as needed."""
     cfg = _config()
     conn = getattr(_local, 'conn', None)
     if conn is None:
-        conn = pymysql.connect(
-            host=cfg['host'],
-            port=cfg.get('port', 3306),
-            user=cfg['user'],
-            password=cfg['password'],
-            database=cfg['name'],
-            autocommit=True,
-            cursorclass=pymysql.cursors.DictCursor,
-            connect_timeout=10,
-            charset='utf8mb4',
-        )
+        conn = _new_conn(cfg)
         _local.conn = conn
     else:
-        conn.ping(reconnect=True)
+        try:
+            conn.ping(reconnect=True)
+        except Exception:
+            try:
+                conn.close()
+            except Exception:
+                pass
+            _local.conn = None
+            conn = _new_conn(cfg)
+            _local.conn = conn
     yield conn