fix: Dedup packets across sources, translate numeric port numbers to names

Packet dedup: track seen packet IDs across all sources. Same packet from
Meshview + MeshMonitor counted once, not twice. Fixes inflated counts.
Portnum: numeric values (3, 4, 71) mapped to names (Position, NodeInfo, Neighbors).
LLM prompt: guidance on normal vs abnormal packet rates per type.

meshai/router.py

@@ -113,6 +113,11 @@ RESPONSE STYLE:
 - ABSOLUTELY NO markdown. No asterisks, no bold, no bullet points with * or -, no numbered lists with 1. 2. 3. Just plain text sentences.
 - NEVER say "Want me to keep going?" — the message system adds this automatically when needed. If you say it yourself, users see it twice.
 - When explaining "X/Y gateways" (like 7/7), explain that it means the node is visible to X out of Y data sources (Meshview and MeshMonitor instances that monitor the mesh). It does NOT mean infrastructure routers or regional gateways.
+- When reporting packet types, ALWAYS use the name (Position, NodeInfo, Telemetry) not the number.
+- Normal position interval: 15-30 minutes (48-96 packets/day). 400+ Position packets in 24h means aggressive position interval, wasting airtime. Tell the user.
+- Normal NodeInfo: every 2-3 hours (8-12/day). 50+ is excessive.
+- Normal NeighborInfo: every 6 hours (4/day). 20+ is aggressive.
+- If a node has high packet volume, explain WHAT the packets are and WHETHER the rate is abnormal compared to normal intervals.
 
 QUESTION TYPES:
 - "How's the mesh?" -> Lead with composite score. Highlight 1-2 biggest issues by name. Summarize each region briefly.