New: Add deps-check and deps-gen commands (fixes #75)

[taylortom]

#75

New

• Added deps-check command to verify module dependencies and peerDependencies against source code analysis
• Added deps-gen command to generate correct dependencies and peerDependencies from source code, with optional --write to update package.json and run npm update
• Both commands support --recursive flag to process all child modules detected via adapt-authoring.json
• Added SimpleCliCommand base class for commands that don't require prerequisites checks or release data
• Added shared utility functions: buildPackageIndex, collectJsFiles, isModule, getModuleDirs

Testing

1. cd into a module directory (e.g. api/) and run npx at-utils deps-check — should report dependency check results
2. From the AAT root, run npx at-utils deps-check --recursive — should check all child modules
3. cd into a module directory and run npx at-utils deps-gen — should show a dry-run of expected dependencies
4. Run npx at-utils deps-gen --write — should update package.json and run npm update
5. From the AAT root, run npx at-utils deps-gen --recursive --write — should process all child modules
6. Run from a non-module directory (no adapt-authoring.json) — should print an error and exit with code 1