rename: cosmic-brain → claude-obsidian

Updates all references across README, CLAUDE.md, ATTRIBUTION.md,
WIKI.md, docs/install-guide.md, wiki/getting-started.md,
plugin.json, marketplace.json, commands/wiki.md, setup-vault.sh,
wiki pages, and renames wiki/meta/cosmic-brain-cover.gif.

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

.claude-plugin/plugin.json

@@ -1,5 +1,5 @@
 {
-  "name": "cosmic-brain",
+  "name": "claude-obsidian",
   "version": "1.2.0",
   "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": {
@@ -7,8 +7,8 @@
     "url": "https://github.com/AgriciDaniel"
   },
   "license": "MIT",
-  "homepage": "https://github.com/AgriciDaniel/cosmic-brain",
-  "repository": "https://github.com/AgriciDaniel/cosmic-brain",
+  "homepage": "https://github.com/AgriciDaniel/claude-obsidian",
+  "repository": "https://github.com/AgriciDaniel/claude-obsidian",
   "keywords": [
     "obsidian",
     "knowledge-base",