Add enemy and training target lifecycle for vertical slice combat smoke

[JOY]

Summary

Make the current training-drone prototype feel like a real combat smoke target.

Scope

• Add spawn, alive, damaged, defeated, respawn, and reset states.
• Show clear target health and defeated state.
• Avoid duplicate target instances after respawn.
• Connect defeat to the existing server-owned reward path.

Acceptance Criteria

• The training target has visible HP and defeated feedback.
• Defeating it triggers only one reward event.
• The target respawns or resets after a bounded delay without duplicates.
• Play Mode smoke verifies reward, HP, death, and respawn.

References

• ROADMAP.md

[JOY]

Implemented a scoped #148 combat smoke lifecycle pass on dev:

• PrototypeCombatTarget now tracks explicit alive, damaged, defeated, and respawning presentation states.
• Target plate now shows state text plus respawn countdown while defeated.
• Respawn resets HP, state, visibility, and respawn timer without spawning a duplicate target.
• Late hit responses against an already-defeated target are ignored visually and shown as respawning instead of applying a second defeat presentation.
• PrototypeCombatTrainingHotkeys now blocks duplicate in-flight hit requests while the Nakama reward response is still pending, reducing duplicate reward risk from animation/fallback timing.
• Updated CHANGELOG.md.

Local review fallback: APPROVED WITH SUGGESTIONS. No blocking issue found. The authoritative reward guard still belongs in Nakama, but the Unity prototype now avoids obvious duplicate local request bursts and shows target lifecycle clearly.

Verification run:

• npm test in backend/nakama: pass
• npm run build in backend/nakama: pass
• markdownlint for public docs: pass
• git diff --check: pass
• touched-file em-dash scan: pass
• tools/windows/check-local-health.ps1 -Strict: pass exit; Unity compile OK, Editor.log tail clean, Nakama/Postgres OK, MCP 8080/8766 listening.

[JOY]

Implemented and merged in PR #171. Verification: markdown lint passed, no em-dash matches in touched files, git diff check passed, local code-review fallback approved, root Unity recompile completed with no C# errors, and Play Mode smoke ran with no errors. Remaining warning is the known Visual Studio UDP messaging warning.