✅ Add multi-NPC Background Life combat and loot

[RANGROO]

Summary

• add dedicated LLM-resolved Background Life combat for 2-6 opted-in nearby NPCs on exactly two sides
• persist encounter participants, individual outcomes, corpse placement state, deterministic locks, acknowledgements, retries, rollback, and future Background Life context
• add separate winner-driven loot resolution using current inventory, shared reservations, and equipped/quest-item exclusions
• record combat, death, and loot in eventlog and each participant's Background Life history
• expose combat participation, initiation, lethal, and loot controls through the shared PHP/Prisma API and PHP NPC editor
• stop scheduling dead NPCs for Background Life
• use the real game-time conversion when the encounter library is loaded outside the normal bootstrap

Companion game-side implementation: Dwemer-Dynamics/CHIM #127

Background Life event chain

eligible opted-in NPCs
→ deterministic participant locks
→ one LLM combat resolution
→ per-NPC CombatOutcome commands
→ game-side outcome acknowledgements
→ retry any unacknowledged command
→ fresh death, health, inventory, and position snapshots
→ verify dead actor and corpse placement
→ open and close the real corpse loot UI
→ verify the actor remains dead
→ inventory-safe loot resolution
→ BackgroundLoot transfer and applied-count acknowledgement
→ suppress an identical replay
→ verify final inventories
→ write eventlog and each participant's Background Life history
→ release locks and restore temporary settings

Live Skyrim AE validation

Local Systems Harness run #11 completed the deterministic three-NPC round trip through the real server/game bridge:

• 1 encounter with all 3 participant outcomes acknowledged
• initiator survived; target was confirmed dead; ally was seriously wounded at 26.25 / 75 health
• one deliberately dropped ally command was delivered by the production retry path
• corpse was placed beside the player
• Skyrim opened and closed the real corpse loot interface, then confirmed the actor remained dead
• 3 gold transferred from the defeated actor to the winner: target 10 → 7, winner 0 → 3
• replaying the identical loot command returned the original applied count without transferring twice
• final inventories, post-combat state, pending-response cleanup, and temporary-setting restoration verified
• 1 encounter, 3 acknowledgements, 1 retry, 1 loot transfer, 0 combat failures, 0 failed actors

The live run also exercised the server-to-plugin command bridge directly, including runtime RefID targeting and fresh game telemetry.

Automated validation

• PHP lint: all 9 changed PHP files pass
• git diff --check: pass
• focused resolver and PostgreSQL schema/transaction probes: pass
• local Systems Harness tests: 14 tests, 54 assertions pass
• scenario JSON parse: pass
• exact PR branch was merge-tested with origin/unstable before publication

Deployment

• live test used the local WSL HerikaServer deployment
• the reusable Systems Harness and corpse-UI instrumentation remain local and are not included in this PR

Known limits

• corpse interaction was automated through Skyrim's actual loot menu rather than manually clicked
• live in-game validation was Skyrim AE only; Skyrim VR was deployed but not run in-game