Pause scheduled LLM work while Skyrim is inactive

[RANGROO]

Problem

HerikaServer's scheduled middle-term service keeps running after Skyrim stops sending game traffic. Its global summary and middle-term connector defaults can use DeepSeek V4 Pro independently of every profile, so the background loop can continue consuming OpenRouter credits while the game is closed.

Discord source: Open Discord thread

Changes

• move shared Skyrim activity tracking into lib/game_activity.php
• use global chimMarkGameActivity() and chimHasRecentGameActivity() APIs from the request path and scheduled middle-term gate
• stop scheduled middle-term memory, Background Life, and memory-compaction LLM work after the existing three-minute activity window expires
• resume the scheduler automatically when normal game traffic updates the same activity marker
• keep Player2 health as a consumer of the shared activity session instead of its owner
• mirror the legacy Player2 option keys and retain compatibility aliases during the rename

The timing and scheduler behavior are unchanged. No schema or configuration migration is required.

Validation

• PHP lint passed for lib/game_activity.php, lib/player2_health.php, main.php, and service/processors/middleterm/entrypoint.php
• existing Player2HealthTest: 2 tests, 7 assertions passed
• focused activity probe: 12 assertions passed for generic state, legacy fallback/mirroring, fresh, stale, and missing activity
• focused Player2 integration probe passed for generic request activity and session arming
• focused inactive scheduler probe confirmed return at the generic activity gate before LLM work
• git diff --check
• CHIM unstable push guard: PR required for sensitive runtime paths, guarded-author history, and open-PR overlap

Deployment and limits

The original two-file implementation was deployed locally and verified through two inactive scheduler cycles. This naming/ownership refactor adds a new shared module and has not been redeployed, so the local WSL runtime does not yet represent this commit.

Active-game resume and in-game behavior remain untested. Draft PR #690 touches the same scheduler file and draft PR #704 touches main.php; GitHub currently reports this branch as cleanly mergeable, but either PR may require rechecking if its branch changes.