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/objects/gold_coin.toml

@@ -0,0 +1,5 @@
+name = "Gold Coin"
+description = "A single gold coin stamped with the crest of Thornwall."
+room = "town:market"
+kind = "treasure"
+takeable = true

world/town/objects/healing_potion.toml

@@ -2,3 +2,7 @@ name = "Healing Potion"
 description = "A small glass vial filled with a shimmering red liquid."
 room = "town:temple"
 kind = "consumable"
+takeable = true
+
+[stats]
+heal_amount = 30

world/town/objects/iron_shield.toml

@@ -0,0 +1,8 @@
+name = "Iron Shield"
+description = "A dented but serviceable round shield bearing the blacksmith's mark."
+room = "town:forge"
+kind = "armor"
+takeable = true
+
+[stats]
+armor = 4

world/town/objects/rusty_sword.toml

@@ -2,3 +2,7 @@ name = "Rusty Sword"
 description = "A battered iron blade with a cracked leather grip. It's seen better days."
 room = "town:cellar"
 kind = "weapon"
+takeable = true
+
+[stats]
+damage = 5