feat: add combat save/load and TUI combat display

[amirna2]

Summary

• Save/load combat state: CombatState and RNGPosition serialized in SaveData, RestoreRNG wired into CLI and TUI load paths. Backward compatible with old saves.
• TUI combat display: Lipgloss bordered boxes for COMBAT (orange health bars), VICTORY (green), DEFEAT (red), and GAME OVER screens. Dynamic combat prompt, game over input blocking, combat-aware line coloring, HP in status bar.
• Game content fixes: Goblin blade becomes takeable after defeat, added "use key on case" / "open case" armory rules, gold counter shown in inventory.

Plan

docs/design/combat-implementation.md — Phase 4, tasks 29-35 (all complete).

Files changed

File	Change
engine/save/save.go	Add Combat + RNGPosition to SaveData, Save(), ApplySave()
engine/save/save_test.go	3 round-trip tests (combat state, RNG position, old save compat)
engine/engine.go	Gold in inventory display
cli/cli.go	RestoreRNG after load, combat in /state, combat in /help
tui/combat.go	New — healthBar, renderCombatStatus, renderVictory, renderDefeat, renderGameOver, injectBorderTitle
tui/style.go	New lineKind values + styles for combat/game-over/pre-styled
tui/tui.go	Combat injection, dynamic prompt, game over blocking, combat-aware coloring
tui/status.go	HP display in status bar
tui/tui_test.go	TestHealthBar, TestInjectBorderTitle
games/lost_crown/enemies.lua	Blade takeable on defeat via SetProp
games/lost_crown/rules.lua	use_key_on_case, open_case_with_key rules
docs/design/combat-implementation.md	Mark phases 1-4 complete

Test plan

• go test ./... — all green
• golangci-lint run — clean
• Playtest: fight goblin → see health bars + orange text + combat prompt
• Playtest: win → see VICTORY box with enemy at 0 HP
• Playtest: die → see DEFEAT box + GAME OVER screen
• Playtest: mid-combat /save → /quit → relaunch → /load → combat resumes
• Playtest: inventory shows gold after loot
• Playtest: take blade works after goblin dies

🤖 Generated with Claude Code