fix: implement persistent SSH key storage with key generation

- Fix 'error in libcrypto' issue by using persistent key files instead of temporary ones
- Add SSH key pair generation feature with 'Generate Key Pair' button
- Add 'View Public Key' button for generated keys with copy-to-clipboard functionality
- Remove confusing 'both' authentication option, now only supports 'password' OR 'key'
- Add persistent storage in data/ssh-keys/ directory with proper permissions
- Update database schema with ssh_key_path and key_generated columns
- Add API endpoints for key generation and public key retrieval
- Enhance UX by hiding manual key input when key pair is generated
- Update HelpModal documentation to reflect new SSH key features
- Fix all TypeScript compilation errors and linting issues

Resolves SSH authentication failures during script execution

.gitignore

@@ -16,6 +16,9 @@
 db.sqlite
 data/settings.db
 
+# ssh keys (sensitive)
+data/ssh-keys/
+
 # next.js
 /.next/
 /out/