refactor(cli)!: rename all skills and agents to consistent ce- prefix (#503)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/copilot-writer.test.ts

@@ -172,7 +172,7 @@ describe("writeCopilotBundle", () => {
     await fs.writeFile(
       path.join(sourceSkillDir, "SKILL.md"),
       `---
-name: ce:plan
+name: ce-plan
 description: Planning workflow
 ---
 
@@ -187,7 +187,7 @@ Run these research agents:
     const bundle: CopilotBundle = {
       agents: [],
       generatedSkills: [],
-      skillDirs: [{ name: "ce:plan", sourceDir: sourceSkillDir }],
+      skillDirs: [{ name: "ce-plan", sourceDir: sourceSkillDir }],
     }
 
     await writeCopilotBundle(tempRoot, bundle)