Expand AI insight: fix broken competitor query, add continuity, 30-day horizon, holidays

- Fix gather_competitor_data() tier filter: it queried tier IN ('primary','secondary'),
  values that never exist (real values are 'own'/'competitor'/'market'), so the
  cheapest-competitor comparison has always silently returned nothing.
- Feed the previous insight back into the prompt so the model can note what's
  changed/resolved instead of repeating itself.
- Extend forecast horizon from 14 to 30 days; add a per-day revenue table
  alongside the existing occupancy table.
- Annotate the occupancy table with UK (England) bank holidays.
- Add a same-channel market-movement section (B.com vs B.com, rack vs rack)
  diffing rates against the last insight's snapshot, threshold £3.
- Add a parsed headline field + insight history list on the Dashboard,
  collapsed to headline/age and expandable to full content.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/api/config.py

@@ -1223,7 +1223,7 @@ class AIInsightsSettingsResponse(BaseModel):
     api_key_set: bool = False
     model: str = "claude-haiku-4-5-20251001"
     schedule_time: str = "07:15"
-    daily_token_budget: int = 5000
+    daily_token_budget: int = 12000
 
 
 class AIInsightsSettingsUpdate(BaseModel):
@@ -1258,7 +1258,7 @@ async def get_ai_insights_settings(
         api_key_set=config.get('_api_key_set', False),
         model=config.get('ai_insights_model', 'claude-haiku-4-5-20251001'),
         schedule_time=config.get('ai_insights_schedule_time', '07:15'),
-        daily_token_budget=int(config.get('ai_insights_daily_token_budget', '5000')),
+        daily_token_budget=int(config.get('ai_insights_daily_token_budget', '12000')),
     )