fix(ui): add GRP_DATA (type 6) to filter dropdown + color tables (#965)

## Bug

Packet type 6 (`PAYLOAD_TYPE_GRP_DATA` per `firmware/src/Packet.h:25`)
was missing from three frontend lookup tables:
- `public/app.js:7` — `PAYLOAD_COLORS` had no entry for 6 → badge color
fell back to `unknown` (grey)
- `public/packets.js:29` — `TYPE_NAMES` (used by the Packets page
type-filter dropdown) had no entry for 6 → "Group Data" missing from the
menu
- `public/roles.js:17,24` — `TYPE_COLORS` and `TYPE_BADGE_MAP` had no
`GRP_DATA` entry → no dedicated CSS class

The packet detail page already handled it (via `PAYLOAD_TYPES` in
`app.js:6` which had `6: 'Group Data'`) so individual GRP_DATA packets
render correctly. The gap was only in the filter UI + badge styling.

## Fix

Add the missing entry in each table. 4 lines across 3 files.

- `app.js`: add `6: 'grp-data'` to `PAYLOAD_COLORS`
- `packets.js`: add `6:'Group Data'` to `TYPE_NAMES`
- `roles.js`: add `GRP_DATA: '#8b5cf6'` to `TYPE_COLORS` and `GRP_DATA:
'grp-data'` to `TYPE_BADGE_MAP`

Color choice `#8b5cf6` (violet) — distinct from GRP_TXT's blue but
visually adjacent so operators read them as related types.

## Verification (rule 18 + 19)

Built server locally, served the JS files, grepped the rendered output:

```
$ curl -s http://localhost:13900/packets.js | grep TYPE_NAMES
const TYPE_NAMES = { ... 5:'Channel Msg', 6:'Group Data', 7:'Anon Req' ... };

$ curl -s http://localhost:13900/app.js | grep PAYLOAD_TYPES
const PAYLOAD_TYPES = { ... 5: 'Channel Msg', 6: 'Group Data', 7: 'Anon Req' ... };

$ curl -s http://localhost:13900/roles.js | grep GRP_DATA
ADVERT: '#22c55e', GRP_TXT: '#3b82f6', GRP_DATA: '#8b5cf6', ...
ADVERT: 'advert', GRP_TXT: 'grp-txt', GRP_DATA: 'grp-data', ...
```

Frontend tests pass: `test-packets.js` 82/82, `test-hash-color.js`
32/32.

## Out of scope

Consolidating the duplicated PAYLOAD_TYPES / TYPE_NAMES tables into a
single source of truth is a separate cleanup. Two parallel name maps
continues to be a footgun (this is the second time a new type's been
added to one but not the other).

Co-authored-by: Kpa-clawbot <bot@example.invalid>

public/app.js

@@ -4,7 +4,7 @@
 // --- Route/Payload name maps ---
 const ROUTE_TYPES = { 0: 'TRANSPORT_FLOOD', 1: 'FLOOD', 2: 'DIRECT', 3: 'TRANSPORT_DIRECT' };
 const PAYLOAD_TYPES = { 0: 'Request', 1: 'Response', 2: 'Direct Msg', 3: 'ACK', 4: 'Advert', 5: 'Channel Msg', 6: 'Group Data', 7: 'Anon Req', 8: 'Path', 9: 'Trace', 10: 'Multipart', 11: 'Control', 15: 'Raw Custom' };
-const PAYLOAD_COLORS = { 0: 'req', 1: 'response', 2: 'txt-msg', 3: 'ack', 4: 'advert', 5: 'grp-txt', 7: 'anon-req', 8: 'path', 9: 'trace' };
+const PAYLOAD_COLORS = { 0: 'req', 1: 'response', 2: 'txt-msg', 3: 'ack', 4: 'advert', 5: 'grp-txt', 6: 'grp-data', 7: 'anon-req', 8: 'path', 9: 'trace' };
 
 function routeTypeName(n) { return ROUTE_TYPES[n] || 'UNKNOWN'; }
 function payloadTypeName(n) { return PAYLOAD_TYPES[n] || 'UNKNOWN'; }

public/packets.js

@@ -26,7 +26,7 @@
   let observers = [];
   let observerMap = new Map(); // id → observer for O(1) lookups (#383)
   let regionMap = {};
-  const TYPE_NAMES = { 0:'Request', 1:'Response', 2:'Direct Msg', 3:'ACK', 4:'Advert', 5:'Channel Msg', 7:'Anon Req', 8:'Path', 9:'Trace', 11:'Control' };
+  const TYPE_NAMES = { 0:'Request', 1:'Response', 2:'Direct Msg', 3:'ACK', 4:'Advert', 5:'Channel Msg', 6:'Group Data', 7:'Anon Req', 8:'Path', 9:'Trace', 11:'Control' };
   function typeName(t) { return TYPE_NAMES[t] ?? `Type ${t}`; }
   const isMobile = window.innerWidth <= 1024;
   const PACKET_LIMIT = isMobile ? 1000 : 50000;

public/roles.js

@@ -15,14 +15,14 @@
   };
 
   window.TYPE_COLORS = {
-    ADVERT: '#22c55e', GRP_TXT: '#3b82f6', TXT_MSG: '#f59e0b', ACK: '#6b7280',
+    ADVERT: '#22c55e', GRP_TXT: '#3b82f6', GRP_DATA: '#8b5cf6', TXT_MSG: '#f59e0b', ACK: '#6b7280',
     REQUEST: '#a855f7', RESPONSE: '#06b6d4', TRACE: '#ec4899', PATH: '#14b8a6',
     ANON_REQ: '#f43f5e', UNKNOWN: '#6b7280'
   };
 
   // Badge CSS class name mapping
   const TYPE_BADGE_MAP = {
-    ADVERT: 'advert', GRP_TXT: 'grp-txt', TXT_MSG: 'txt-msg', ACK: 'ack',
+    ADVERT: 'advert', GRP_TXT: 'grp-txt', GRP_DATA: 'grp-data', TXT_MSG: 'txt-msg', ACK: 'ack',
     REQUEST: 'req', RESPONSE: 'response', TRACE: 'trace', PATH: 'path',
     ANON_REQ: 'anon-req', UNKNOWN: 'unknown'
   };