docs(combat): record recovery architecture and issue scope

[MoonlightByte]

Summary

• preserves the complete mainline-only combat architecture and regression assessment
• records the recovered legacy player-experience contract and current deterministic substrate
• defines the target agentic encounter-manifest boundary, C4 maps, issue ledger, stop gates, and native-Windows acceptance matrix
• explicitly excludes aborted/non-main combat branches from design authority

Umbrella issue: #191

Verification

• git diff --check -- docs/architecture/combat-system-recovery-master.md
• documentation-only; no runtime behavior changed

No merge requested. This draft is the review gate before combat implementation resumes.