chore: simplify .gitignore for personal vault, add plugins

Cleaned up .gitignore (removed upstream author-specific entries, added
.claude/ and excalidraw main.js). Track installed Obsidian plugins:
dataview, templater, obsidian-git, local-rest-api.

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

.obsidian/community-plugins.json

@@ -2,5 +2,9 @@
   "obsidian-excalidraw-plugin",
   "obsidian-banners",
   "calendar",
-  "thino"
-]
+  "thino",
+  "templater-obsidian",
+  "dataview",
+  "obsidian-git",
+  "obsidian-local-rest-api"
+]