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/autoresearch/SKILL.md

@@ -8,6 +8,7 @@ description: >
   Triggers on: "/autoresearch", "autoresearch", "research [topic]", "deep dive into [topic]",
   "investigate [topic]", "find everything about [topic]", "research and file",
   "go research", "build a wiki on".
+allowed-tools: Read Write Edit Glob Grep WebFetch WebSearch
 ---
 
 # autoresearch: Autonomous Research Loop