refactor(skills): extract skill logic into standalone agent files

Skills now delegate to agent .md files instead of embedding logic
inline. Added new agents (bugfixer, code-cleaner, commit-changer,
doc-syncer, feater, hotfixer, seo-analyzer) and new skills
(code-clean, doc, seo). Replaced /readme with /doc (broader scope).

Co-Authored-By: Claude <noreply@anthropic.com>

skills/seo/SKILL.md

@@ -0,0 +1,28 @@
+---
+name: seo
+description: |
+  Full SEO audit and optimization for any web project. Detects framework,
+  audits all SEO signals (meta, OG, structured data, sitemap, robots.txt,
+  headings, alt attrs, canonicals, hreflang), applies fixes directly in code,
+  and generates a strategic SEO guide.
+  Trigger: "seo", "referencement", "optimize for search", "audit SEO",
+  "meta tags", "structured data", "JSON-LD", "sitemap", "robots.txt",
+  "Google ranking", "local SEO", "referencement local", "fiche Google".
+  For code-only bugs → use /bugfix. For feature work → use /feat.
+argument-hint: optional keywords/scope, e.g. "local SEO plombier 91 94 77"
+allowed-tools:
+  - Read
+  - Edit
+  - Write
+  - Bash
+  - Grep
+  - Glob
+  - Agent
+---
+
+Load and follow strictly:
+- $HOME/.claude/agents/seo-analyzer.md
+
+Execute the SEO-ANALYZER agent on the following target:
+
+$ARGUMENTS