Expand equipment variants, add region system, fix vendor overlap, and implement missing skill passives

[phaax]

• Remove arrow item; bows (short_bow, sling, crossbow, elven_longbow, death_bow) are self-sufficient ranged weapons
• Replace ranger starting arrow with sling as secondary ranged option
• Add ~60 new items: 19 weapons, 10 armor, 8 helmets (filling empty SLOT.HELMET), 9 accessories, 5 consumables — all with region or property tags where appropriate
• Add region field to Item interface and tag items: mountain (dwarven), forest (elven), desert (scimitar/obsidian), swamp (bone), arctic (frost), coastal (fisherman)
• Completely redesign shop tier tables with strict role separation: blacksmith=weapons+armor only, healer=potions+herbs only, tavern=food only, general=survival basics
• Add biomeToRegion() in worldgen.ts; store loc.region on every town at world-gen time
• Pass shopRegion from loc onto all vendor NPC objects in towngen.ts
• Filter region-tagged items in getShopInventoryByRole() — regional gear only appears in matching towns
• Implement Bargaining skill in shopScreen: 15% buy discount, 65% sell rate (up from 50%)
• Implement Lockpicking loot quality bonus: +15% drop chance multiplier in collectLoot()
• Implement Tracking/Archery initiative: surprise enemies on combat start (30% chance to skip their first attack)
• Implement Herbalism forage ability: grants 1–3 healing herbs once per combat area
• Update monster loot tables with new items (helmets, regional armor, accessories) for better variety

https://claude.ai/code/session_01156B541GgnueY6r6vfH2Jf