Fix heading, scope, version placement, and consistency across policy docs

- Rename REPO_POLICIES.md heading from "Development Policies" to
  "Repository Policies" to distinguish from code styleguides
- Move version line above heading per convention
- Add scope statement and links to code styleguide documents
- Add missing Makefile and LICENSE to minimum files list
- Add version lines to all cross-project docs (CODE_STYLEGUIDE*.md,
  GO_HTTP_SERVER_CONVENTIONS.md)
- Clean up CODE_STYLEGUIDE.md heading (was old repo name)
- Update EXISTING_REPO_CHECKLIST.md link text to match new heading

prompts/REPO_POLICIES.md

@@ -1,7 +1,19 @@
-# Development Policies
-
 Version: 2026-02-22
 
+# Repository Policies
+
+This document covers repository structure, tooling, and workflow standards. Code
+style conventions are in separate documents:
+
+- [Code Styleguide](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE.md)
+  (general, bash, Docker)
+- [Go](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_GO.md)
+- [JavaScript](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_JS.md)
+- [Python](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/CODE_STYLEGUIDE_PYTHON.md)
+- [Go HTTP Server Conventions](https://git.eeqj.de/sneak/prompts/raw/branch/main/prompts/GO_HTTP_SERVER_CONVENTIONS.md)
+
+---
+
 - Cross-project documentation (such as this file) must include a
   `Version: YYYY-MM-DD` line near the top so it can be kept in sync with the
   authoritative source as policies evolve.
@@ -143,7 +155,8 @@ Version: 2026-02-22
 
 - New repos must contain at minimum:
     - `README.md`, `.git`, `.gitignore`, `.editorconfig`
-    - `REPO_POLICIES.md` (copy from the `prompts` repo)
+    - `LICENSE`, `REPO_POLICIES.md` (copy from the `prompts` repo)
+    - `Makefile`
     - `Dockerfile`, `.dockerignore`
     - `.gitea/workflows/check.yml`
     - Go: `go.mod`, `go.sum`, `.golangci.yml`