feat: consolidate /accounts into /account-limits endpoint

- Remove redundant /accounts endpoint
- Enhance /account-limits table output with account status, last used time, and quota reset time
- Filter model list to show only Claude models
- Use local time format for timestamps
- Update documentation (README.md, CLAUDE.md, index.js)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/account-manager.js

@@ -619,6 +619,15 @@ export class AccountManager {
     getSettings() {
         return { ...this.#settings };
     }
+
+    /**
+     * Get all accounts (internal use for quota fetching)
+     * Returns the full account objects including credentials
+     * @returns {Array<Object>} Array of account objects
+     */
+    getAllAccounts() {
+        return this.#accounts;
+    }
 }
 
 export default AccountManager;