feat(world): annotate lamp/matches/letter for read/light/extinguish

Adds the new schema flags and per-state body sections so the dispatcher's
new verb handlers have content to narrate.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/world/items/lamp.md

@@ -3,8 +3,15 @@ id: lamp
 names: ["lamp", "oil lamp", "torch"]
 short: "an oil lamp"
 takeable: true
+lightable: true
 initialState:
   lit: false
 ---
 
 An iron oil lamp with a glass chimney. Currently unlit.
+
+## lit
+The wick catches. Warm yellow light pushes the dark back.
+
+## extinguished
+You smother the wick. The room closes around you again.