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>

skills/wiki/SKILL.md

@@ -7,6 +7,7 @@ description: >
   Triggers on: "set up wiki", "scaffold vault", "create knowledge base", "/wiki",
   "wiki setup", "obsidian vault", "knowledge base", "second brain setup",
   "running notetaker", "persistent memory", "llm wiki".
+allowed-tools: Read Write Edit Glob Grep Bash
 ---
 
 # wiki: Claude + Obsidian Knowledge Companion