feat(suggestions): group wip/banner/editor under a separate 'system' category

System tags are kind=general, so their suggestions previously landed in the
General group. Give them their own 'system' suggestion category so the operator
reviews them apart from content tags: _current_heads maps is_system heads to
category 'system' (still trained as general heads, still gated by the 0.65
floor). Frontend: CATEGORY_ORDER/LABELS gain 'system'; SuggestionsPanel renders
a 'System' group first (small, collapsible, open — false positives easy to spot
and reject); the typed-dropdown shows the shield icon for system entries. Safe:
system-tag suggestions always carry a canonical_tag_id, so the create-by-kind
path (which would send 'system' as a TagKind) is never hit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

frontend/src/stores/suggestions.js

@@ -5,11 +5,13 @@ import { useApi } from '../composables/useApi.js'
 import { useAsyncAction } from '../composables/useAsyncAction.js'
 import { useInflightToken } from '../composables/useInflightToken.js'
 
-// Category display order: people first, general last.
-// 'artist' (FC-2d-vii-c) and 'copyright' (2026-06-01) retired — only
-// character and general surface as suggestion categories now.
-export const CATEGORY_ORDER = ['character', 'general']
+// Category display order: system (hygiene flags) first for quick review, then
+// people, general last. 'artist' (FC-2d-vii-c) and 'copyright' (2026-06-01)
+// retired. 'system' groups the wip/banner/editor hygiene tags apart from content
+// tags (they're kind=general on the backend but surface under their own category).
+export const CATEGORY_ORDER = ['system', 'character', 'general']
 export const CATEGORY_LABELS = {
+  system: 'System',
   character: 'Character',
   general: 'General'
 }