Decode advert node type as enum; add sensor type; drop empty packets

[ajvpot]

Advert node type: enum, not bit flags

The advert app_data flags byte (Core Protocol §2.8.3) uses split encoding: the low 4 bits are an integer node-type enum and the high 4 bits are independent presence flags.

bits 0-3 (0x0F): node type — 0=none, 1=chat/companion, 2=repeater, 3=room server, 4=sensor
bit 4 (0x10): has_location   bit 5 (0x20): feature1   bit 6 (0x40): feature2   bit 7 (0x80): has_name

The decode treated the type as independent bit flags (is_chat_node = flags & 0x01, is_repeater = flags & 0x02, is_room_server = flags & 0x03). Because a room server is type 3 (0b0011) it matched all three at once (shown as repeater + companion + room simultaneously), and a sensor (type 4) matched none (rendered as an untyped/unknown node).

Migration 008 corrects the derivation in the meshcore_adverts / meshcore_adverts_latest views, adds an is_sensor boolean and a node_type column, and carries neighbor_is_sensor onto the direct-neighbor graph. These are read-time view changes over already-stored data (appdata_flags / payload), so the fix applies retroactively to all history with no reingest or backfill. The presence-flag (has_*) decoding was already correct and is unchanged. Full Down restores the prior view/MV definitions.

The UI gains a sensor badge (node page, node cards, advert details), getNodeType is corrected, and is_sensor is threaded through the node/neighbor/search/streaming queries, types, and API docs. Grafana reads is_repeater/is_room_server straight from the view, so its node-type counts self-correct on the next refresh.

Ingest: drop empty packets

A growing share of upstream publishers (observer nodes, repeater tx-confirmations) emit an otherwise-valid JSON envelope with an empty/absent packet-bytes field. Stored, these decode to an empty payload and a degenerate packet_hash and carry no signal. enqueuePacket now drops zero-byte packets, counted and logged via droppedEmpty. (Confirmed by sampling the live feeds: the bytes are simply not present upstream — not a renamed field — so nothing decodable is lost.)

Validation

• Full migration chain applied → rolled back to 7 → re-applied cleanly on a throwaway ClickHouse; new columns present on all three objects.
• A synthetic room-server advert (flags 0x03) decodes to node_type=3, is_room_server=1 with is_chat_node=0, is_repeater=0 (previously chat+repeater+room all 1).
• Decode logic cross-checked against real data: every node maps to exactly one type; no more chat∧repeater overlap.
• tsc --noEmit + lint clean; go build + go test pass (incl. new empty-drop test).

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