feat(mqtt): add per-slot packet filters for MQTT slots

Introduce per-slot packet filters to allow users to specify which
packet types are uploaded for each MQTT slot. This feature enhances
the flexibility of the MQTT bridge by enabling users to configure
allowlists for packet types, improving the efficiency of data
transmissions. The implementation includes updates to the WebConfig
interface, internal handling of packet filters, and necessary
modifications to the MQTT preferences structure.

scripts/webconfig_mock_server.py

@@ -48,7 +48,7 @@ LEN_LIMITS = {
     "mqtt.email": 63, "mqtt.ntp": 63, "timezone": 31, "snmp.community": 23,
 }
 SLOT_LEN_LIMITS = {"server": 63, "username": 31, "password": 63,
-                   "token": 47, "topic": 95, "audience": 63}
+                   "token": 47, "topic": 95, "audience": 63, "filter": 37}
 
 # Preset names + what the UI must collect (mirrors handlePresets()).
 PRESETS = (
@@ -99,7 +99,8 @@ def default_config(setup_mode):
 
 def _slot():
     return {"preset": "none", "server": "", "port": 8883, "username": "",
-            "password": "", "token": "", "topic": "", "audience": ""}
+            "password": "", "token": "", "topic": "", "audience": "",
+            "filter": "all"}
 
 
 class State:
@@ -253,6 +254,26 @@ def apply_set(cfg, key, val):
     return True, "OK"   # unknown-but-allowlisted: accept (mock is lenient here)
 
 
+def canonical_packet_filter(val):
+    stripped = val.strip()
+    if stripped == "" or stripped == "all":
+        return "all"
+    if stripped == "none":
+        return "none"
+    mask = 0
+    for part in stripped.split(","):
+        token = part.strip()
+        if not re.fullmatch(r"[0-9]+", token):
+            return None
+        packet_type = int(token)
+        if packet_type > 15:
+            return None
+        mask |= 1 << packet_type
+    if mask == 0xFFFF:
+        return "all"
+    return ",".join(str(i) for i in range(16) if mask & (1 << i))
+
+
 def apply_slot_set(cfg, idx, field, val):
     slot = cfg["mqtt"]["slots"][idx]
     if field in SLOT_LEN_LIMITS and len(val) > SLOT_LEN_LIMITS[field]:
@@ -266,6 +287,12 @@ def apply_slot_set(cfg, idx, field, val):
             return False, "Error: port must be between 1 and 65535"
         slot["port"] = p
         return True, "OK"
+    if field == "filter":
+        canonical = canonical_packet_filter(val)
+        if canonical is None:
+            return False, "Error: filter must be all, none, or CSV packet types 0-15"
+        slot["filter"] = canonical
+        return True, "OK - slot %d packet types: %s" % (idx + 1, canonical)
     if field in ("preset", "server", "username", "password", "token", "topic", "audience"):
         slot[field] = val
         if field == "token":