Increases the robustness of NIP-07 extension detection by implementing a retry loop in `NostrClient.login`. If the initial detection (default 5s) times out, the client will retry up to 3 times with a 1-second delay between attempts, effectively handling slower injection scenarios or race conditions during page load.
- Modified `js/nostr/client.js` to wrap `waitForNip07Extension` in a retry loop.
- Validated with a reproduction test case simulating late injection.