chore: apply Anthropic best practices to all skills (v1.4.2)

- Add `allowed-tools` frontmatter to all 10 SKILL.md files for tool pre-approval
- Soften kepano/obsidian-skills dependency in 4 skills (canvas, obsidian-bases, obsidian-markdown, wiki-ingest) — now recommends if installed, doesn't require
- Soften banana-claude dependency in canvas skill
- Improve trigger descriptions for defuddle (+4 phrases) and obsidian-markdown (+5 phrases)
- Remove docs/superpowers/plans/ (contained private paths)
- Gitignore claude-obsidian-archive/ and _attachments/
- Bump version to 1.4.2

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -81,3 +81,9 @@ Claude SEO*.png
 
 # Private Skool Hub assets — not for public repos
 _attachments/images/skool-hub/
+
+# Archive of old versions (cosmic-brain, GIF assets)
+claude-obsidian-archive/
+
+# User-specific attachments
+_attachments/