feat(campaigns): add the campaign template

A campaign holds only play state and names its game in frontmatter;
new-campaign copies this template.

campaigns/_template/world/factions/README.md

@@ -0,0 +1,21 @@
+# Factions
+
+One file per faction, named `kebab-case.md`.
+
+```markdown
+---
+name: 
+goal: 
+disposition: friendly | neutral | hostile | unknown
+---
+
+# <name>
+
+## Description
+
+## Members
+
+## Resources
+
+## History
+```

campaigns/_template/world/locations/README.md

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+# Locations
+
+One file per location, named `kebab-case.md`. Keep the frontmatter stable so
+the agent can update it in place.
+
+```markdown
+---
+name: 
+type: 
+region: 
+status: visited | known | rumored
+---
+
+# <name>
+
+## Description
+
+## Notable features
+
+## Inhabitants
+
+## History
+```

campaigns/_template/world/npcs/README.md

@@ -0,0 +1,23 @@
+# NPCs
+
+One file per NPC, named `kebab-case.md`.
+
+```markdown
+---
+name: 
+role: 
+location: 
+status: alive | dead | missing | unknown
+disposition: friendly | neutral | hostile | unknown
+---
+
+# <name>
+
+## Description
+
+## Wants
+
+## Relationships
+
+## History
+```