docs: fix stale milla-jovovich org URLs in website and plugin manifests (#787)

Follow-up to #766 which covers version.py, pyproject.toml, README,
CHANGELOG, and CONTRIBUTING. These 11 files still had the old org
name in URLs:

- website/ (VitePress config + 6 docs pages)
- .claude-plugin/ (plugin.json repository, README marketplace command)
- .codex-plugin/ (plugin.json URLs, README links)

Author name fields are intentionally unchanged.

.claude-plugin/README.md

@@ -11,7 +11,7 @@ A Claude Code plugin that gives your AI a persistent memory system. Mine project
 ### Claude Code Marketplace
 
 ```bash
-claude plugin marketplace add milla-jovovich/mempalace
+claude plugin marketplace add MemPalace/mempalace
 claude plugin install --scope user mempalace
 ```
 

.claude-plugin/plugin.json

@@ -25,5 +25,5 @@
     "palace",
     "search"
   ],
-  "repository": "https://github.com/milla-jovovich/mempalace"
+  "repository": "https://github.com/MemPalace/mempalace"
 }