Rewrite AGENTS.md to reflect current project structure and guide agents to key file locations

[sebastientaggart]

AGENTS.md was written early in the project and hasn't kept pace with how CodeCannon has grown. Agents working on the project waste time searching for files (e.g. 'where is the installation documentation?') because AGENTS.md doesn't tell them where things live.

Key problems:

• Branch strategy still says 'development' instead of 'dev'
• No mention of the docs/ directory, .codecannon.yaml, VERSION, Makefile, or ROADMAP.md
• No file location guide — agents don't know where documentation, config, or generated output live
• Missing description of skill anatomy (frontmatter, placeholders, conditionals)
• No adapter overview or output path documentation
• Testing instructions reference a specific consumer project instead of explaining the general pattern
• Thin guardrails section

The rewrite will give agents a clear, current map of the project so they can orient themselves immediately instead of exploring.

[sebastientaggart]

Agent Implementation Notes

File to change: AGENTS.md (root)

Approach: Full rewrite of the single file. Structure:

1. Header — one-line project description
2. Branch Strategy — corrected to feature/* → dev → main
3. Where Things Live — comprehensive file location guide organized by purpose (source skills, adapters, config, docs, generated output, build/workflow, meta). This is the key addition — prevents agents from searching aimlessly.
4. Skill Anatomy — frontmatter fields, placeholder syntax ({{NAME}}), conditional blocks ({{#if}}/{{/if}}), hash markers
5. Working on Code Cannon — updated sections for editing skills, adding adapters, adding placeholders, adding new skills. Use make check/make dev/make sync instead of raw sync.sh commands.
6. Self-hosting — updated to mention all adapter outputs, not just .claude/commands/
7. What Agents Must Never Do — expanded guardrails
8. Project Layout — complete tree including docs/, .codecannon.yaml, VERSION, Makefile, ROADMAP.md

Key decisions:

• Keep it concise — AGENTS.md should be a quick-reference map, not a tutorial. Point to docs/ for deep dives.
• Focus on 'where is X' answers since that's the main pain point observed.
• Don't duplicate content from docs/ — reference it.