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.

src/world/items/letter.md

@@ -3,6 +3,10 @@ id: letter
 names: ["letter", "folded letter", "paper"]
 short: "a folded letter"
 takeable: true
+readable: true
 ---
 
+A folded letter. The wax seal has been broken once already.
+
+## read
 A folded letter on yellowed paper. The hand is unfamiliar. It reads: "Come at once. The thing in the cellar is waking."

src/world/items/matches.md

@@ -3,6 +3,13 @@ id: matches
 names: ["matches", "safety matches", "box"]
 short: "a box of safety matches"
 takeable: true
+lighter: true
+lighterUses: 4
+initialState:
+  uses: 4
 ---
 
 A small cardboard box of safety matches. Half-full.
+
+## lighter-empty
+The last match flares, burns down, and goes out. The book is empty.