fix(spot): stop quadratic hidden_points growth and backward timestamp rollback

[techtimo]

Problem

The SPOT (findmespot) crawler uses does_point_exist($spot_id) to detect already-processed messages. The rolling-anchor dedup in insert_row() absorbs stationary TRACK pings by updating the previous row without inserting a new row, so the SPOT message ID is never stored in the DB.

Consequence 1 — quadratic hidden_points growth:
On every subsequent cron tick, those unrecognised IDs are not found by does_point_exist, so the anchor fires again and hidden_points increments once per unrecognised ID per run. With N absorbed pings and K cron runs, total hidden_points = N × K, growing quadratically. This explains the 762 hidden-points accumulation reported on Reynald's stationary SPOT feed.

Consequence 2 — anchor timestamp rolls backward:
The SPOT API returns messages newest-first. Rolling anchor overwrites the anchor row's time with each incoming (older) timestamp, leaving the anchor row with the oldest stationary ping's time instead of the newest. On the next cron tick this causes an artificially large time_diff, which breaks the anchor threshold and forces an unnecessary new row insertion.

Fix

class-spotmap-api-crawler.php — when insert_point() returns 0 (rolling anchor absorbed), treat the point as fully accounted for and break the pagination loop. Reduces per-cron reprocessing from O(N²) to O(1).

class-spotmap-database.php — in the rolling anchor update, skip overwriting time if the incoming timestamp is older than the stored one. This keeps the anchor row at the newest observed time regardless of API delivery order.

Test plan

• npm run test:php — 208 tests, 532 assertions, all green before and after
• Verify Reynald's feed: after the next cron tick hidden_points should increment by at most 1, not by N
• Verify anchor row time column reflects the latest ping time, not an older one

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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