Chore: Ignore AI tooling caches and DocC build output

- Ignore per-developer AI config: .claude/, .cursor/, .serena/, .vscode/, .windsurfrules, AGENTS.md
- Ignore WHATS-NEXT.md (developer scratchpad)
- Ignore /docc-output/ (CI build artifact, not source)

.gitignore

@@ -9,6 +9,7 @@ DerivedData/
 
 # DocC generated output
 /docs-output/
+/docc-output/
 
 # Docs site (Astro)
 docs/node_modules/
@@ -23,6 +24,15 @@ logo-prompt.md
 session-*.md
 *.backup
 
+# AI tooling / local caches (per-developer)
+.claude/
+.cursor/
+.serena/
+.vscode/
+.windsurfrules
+AGENTS.md
+WHATS-NEXT.md
+
 # Local tooling
 papers/
 .gource/