feat: Go project scaffolding - module init, directory structure, CLI skeleton, Makefile, CI

Co-authored-by: multica-agent <github@multica.ai>

README.md

@@ -1,2 +1,44 @@
 # ExploreDNS
 
+DNS reconnaissance and exploration tool.
+
+## Build
+
+```sh
+go build -o bin/exploredns ./cmd/exploredns
+```
+
+Or use the Makefile:
+
+```sh
+make build
+```
+
+## Usage
+
+```sh
+./bin/exploredns <domain>
+```
+
+## Development
+
+```sh
+make test    # run tests
+make lint    # run go vet
+make clean   # remove build artifacts
+```
+
+## Project Structure
+
+```
+cmd/exploredns/        CLI entry point
+internal/dns/          DNS query operations
+internal/traverse/     DNS tree traversal
+internal/fingerprint/  DNS server fingerprinting
+internal/output/       Result formatting and output
+internal/config/       Configuration management
+```
+
+## License
+
+MIT