Keep template AI guidance optional by default

This template should stay neutral about agent tooling. Instead of shipping opinionated AGENTS.md or CLAUDE.md files, the README now briefly notes that downstream projects can add them later if they want project-specific guidance.

Constraint: Template repos should avoid baking in one team's AI workflow preferences
Rejected: Ship placeholder AGENTS.md and CLAUDE.md files | still adds default agent surface area to every generated project
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: Keep AI-tooling guidance optional unless the template itself depends on it
Tested: make check
Not-tested: PR rendering on GitHub

Author: yujeongdev

README.md

@@ -59,6 +59,11 @@ Let's build something fun, Yujeong.
 └── uv.lock
 ```
 
+## Optional AI guidance files
+
+If your real project wants agent-specific instructions, add `AGENTS.md` and/or `CLAUDE.md` later
+with project-specific guidance. This template does not ship opinionated defaults for them.
+
 ## Quality defaults
 
 This template is intentionally strict by default: