feat: add the-ballad-of-chalk campaign

Cloud Empress campaign for 弗莱格, a sellsword obsessed with chalk.
Ships the brief, PC sheet, state files, a starting location, and the
session 0001 log. The opening hook and hidden truth live in gm/.

campaigns/the-ballad-of-chalk/world/locations/README.md

@@ -0,0 +1,26 @@
+# Locations
+
+One file per location, named `kebab-case.md`. Keep the frontmatter stable so
+the agent can update it in place.
+
+These files are player-facing: record what the PC has observed or could observe.
+A hidden truth the PC has not yet learned belongs in `../../gm/`.
+
+```markdown
+---
+name: 
+type: 
+region: 
+status: visited | known | rumored
+---
+
+# <name>
+
+## Description
+
+## Notable features
+
+## Inhabitants
+
+## History
+```