perf: denormalize post_status into event_dates to eliminate posts table JOIN

[chubes4]

Summary

• Add post_status column to datamachine_event_dates table with composite (post_status, start_datetime) index
• Skip the 130K-row posts table JOIN in date-filtered queries by using ed.post_status = 'publish' directly
• Sync post_status on transition_post_status hook to keep denormalized column in sync

Problem

The events site has 37K events in event_dates and 130K rows in the posts table. Every event count/aggregation query JOINed posts just to filter post_type = 'data_machine_events' AND post_status = 'publish', but the 128MB InnoDB buffer pool couldn't cache all those pages, causing 2-4s per query from disk reads.

Changes

File	Change
EventDatesTable.php	Add post_status column to schema, upsert(), update_status(), backfill()
meta-storage.php	Add transition_post_status hook to keep status in sync
DateFilter.php	Add $include_status and $join_column params to upcoming_sql(), past_sql(), date_range_sql()
Taxonomy_Helper.php	Skip posts JOIN when date filter is active; use tr.object_id for cross-filter JOINs
UpcomingCountAbilities.php	Skip posts JOIN, use ed.post_status directly

Benchmarks (37K events, 257 location terms)

Query	Before	After	Improvement
Location term counts	2.9s	107ms	27x
Cross-filter counts	3.7s	174ms	21x

Migration

Schema change applied live. Backfill (UPDATE ed SET post_status = p.post_status) affected 805 rows (non-published events that were defaulting to 'publish').

Backward Compatibility

• DateFilter::upcoming_sql() etc. default to include_status=true, join_column='p.ID' — existing callers that still JOIN posts are unaffected
• EventDatesTable::upsert() auto-detects post_status from the post if not provided — existing callers don't need changes