Consolidate noise floor data into packetStore — remove split across two stores

[zindello]

Problem

Noise floor data currently lives in two stores:

• systemStore.noiseFloorDbm — a computed that reads stats.noise_floor_dbm from the WebSocket stats payload. This is the live current reading.
• packetStore.noiseFloorHistory / packetStore.currentNoiseFloor — historical readings fetched from the packets API on load, plus the zero-filtering / consecutive-bad-polls guard logic.

NoiseFloorSparkline has to stitch both together:

// live value from system store, filtered value from packet store
const currentValue = computed(() => systemStore.noiseFloorDbm || packetStore.currentNoiseFloor)

This split caused a bug (?? vs ||) because systemStore.noiseFloorDbm can be 0 (an invalid reading), bypassing the bad-poll guard that only lives in packetStore. It will keep being a source of confusion.

Where the data should live

packetStore is the right home. Noise floor is packet-layer RF data — it belongs alongside packet stats, not system/config stats. packetStore already owns the history, the dedup logic, the zero filter, and the bad-poll guard. It should own the live value too.

Proposed fix

1. When the WebSocket stats payload includes noise_floor_dbm, the handler (currently in systemStore) should call packetStore.appendNoiseFloorReading(dbm) rather than writing to stats.noise_floor_dbm.
2. Remove noiseFloorDbm from systemStore entirely.
3. NoiseFloorSparkline reads only from packetStore.currentNoiseFloor — single source of truth, zero-filtering included.
4. The watch(() => systemStore.noiseFloorDbm, ...) in NoiseFloorSparkline that feeds WS readings into the packet store can also be removed — the data service / WS handler does it directly.

Files to touch

• src/stores/system.ts — remove noiseFloorDbm computed and the WS assignment
• src/stores/dataService.ts (or wherever the WS stats handler lives) — call packetStore.appendNoiseFloorReading() on incoming noise floor readings
• src/components/nav/NoiseFloorSparkline.vue — remove systemStore import and watch, simplify currentValue to packetStore.currentNoiseFloor