security: add .gitignore rules to prevent secret/dotfile commits

Add comprehensive .gitignore rules to prevent accidental commits of:
- Shell history files (.bash_history, .python_history)
- SSH keys and known_hosts
- Git credentials and Gitea tokens
- Editor state files (.viminfo, .selected_editor)
- Environment files (.env, .env.*, except .env.example)
- TLS private keys (*.pem, *.key)
- Telegram config directory
- Hermes auth/env files
- Other sensitive home directory dotfiles

No secrets were found currently tracked; this is a preventive measure.

.gitignore

@@ -10,3 +10,27 @@ __pycache__/
 
 # Generated audit reports
 reports/
+
+# Secrets and credentials
+.bash_history
+.git-credentials
+.gitea_token
+.ssh/id_*
+.ssh/known_hosts
+.viminfo
+.wget-hsts
+.profile
+.bashrc
+.bash_logout
+.python_history
+.lesshst
+.selected_editor
+.sudo_as_admin_successful
+.config/telegram/
+.hermes/.env
+.hermes/auth.json
+*.pem
+*.key
+.env
+.env.*
+!.env.example