Fix review issues: front matter, headings, consistency, typos

- Move title and last_modified to YAML front matter (all policy docs)
- Make all document sections H1, subsections H2
- Update version rule to reference front matter format
- Fix "our" → "your" typo in Go styleguide
- Fix Python styleguide numbering (2. → 1.)
- Fix README: "flat collection" → accurate description, remove stale TODO
- Remove Makefile items from code styleguides (repo stuff, not code),
  add note linking to Repository Policies
- Change zerolog → slog in Go styleguide
- Fix JS styleguide npm reference: both work, but use make targets
- Drop .json from healthcheck path, add JSON content-type requirement
- Add Author/License to Go HTTP Server Conventions
- Convert hyperlinks to backtick URLs in checklists for consistency
- Add version/front matter to both checklists

README.md

@@ -48,15 +48,14 @@ share, and evolve prompts across projects.
 
 ## Design
 
-The repository is a flat collection of Markdown files. Each file contains one or
-more related prompts or policy documents. There is no build step or runtime
-component; the prompts are consumed by copying them into other projects or
-referencing them directly.
+The repository is a collection of Markdown files organized in the `prompts/`
+subdirectory. Each file contains one or more related prompts or policy
+documents. There is no build step or runtime component; the prompts are consumed
+by copying them into other projects or referencing them directly.
 
 ## TODO
 
 - Add more prompt templates for common development tasks
-- Add CI to lint Markdown
 
 ## License