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>

.claude-plugin/plugin.json

@@ -1,6 +1,6 @@
 {
   "name": "claude-obsidian",
-  "version": "1.4.1",
+  "version": "1.4.2",
   "description": "Claude + Obsidian knowledge companion. Sets up a persistent, compounding wiki vault. Covers memory management, session notetaking, knowledge organization, and agent context across projects. Based on Andrej Karpathy's LLM Wiki pattern.",
   "author": {
     "name": "AgriciDaniel",