Add SQLite persistence, per-player NPC attitude system, character creation, and combat

- Add trait-based DB layer (db.rs) with SQLite backend for easy future swapping
- Player state persisted to SQLite: stats, inventory, equipment, room position
- Returning players skip chargen and resume where they left off
- Replace boolean hostile flag with 5-tier attitude system (friendly/neutral/wary/aggressive/hostile)
- Per-player NPC attitudes stored in DB, shift on kills with faction propagation
- Add character creation flow (chargen.rs) with data-driven races and classes from TOML
- Add turn-based combat system (combat.rs) with XP, leveling, and NPC respawn
- Add commands: take, drop, inventory, equip, use, examine, talk, attack, flee, stats
- Add world data: 5 races, 4 classes, hostile NPCs (rat, thief), new items

Made-with: Cursor

world/town/npcs/barkeep.toml

@@ -1,4 +1,7 @@
 name = "Grizzled Barkeep"
 description = "A weathered man with thick forearms and a permanent scowl. He polishes the same mug endlessly."
 room = "town:tavern"
-dialogue = "Welcome to The Rusty Tankard. We've got ale, and we've got stronger ale. Pick one."
+base_attitude = "friendly"
+
+[dialogue]
+greeting = "Welcome to The Rusty Tankard. We've got ale, and we've got stronger ale."