Initial MVP implementation of Claudia Docs CLI

- Auth commands: login, logout, status
- Document commands: create, list, get, update, delete
- Project commands: list, get
- Folder commands: list, create
- Tag commands: list, create, add
- Search command
- Reasoning save command
- JSON output format with --output text option
- Viper-based configuration management
- Cobra CLI framework

.gitignore

@@ -0,0 +1,25 @@
+# Binaries
+claudia-docs
+*.exe
+*.dll
+*.so
+*.dylib
+
+# Test binary
+*.test
+
+# Output
+*.out
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Vendor (if using)
+/vendor/