feat: concurrent Windows collection, platform tests, and CLI improvements (#10)

* feat: sign distribution binary

* feat: add distribution .pkg with Apache 2.0 license and installer UI

- Add installer resources (welcome.html, readme.html, license.html)
- Convert Apache 2.0 LICENSE to HTML for macOS Installer.app display
- Add Distribution XML for productbuild with Welcome, Read Me, and
  License Agreement screens
- Update Makefile build-dist-pkg to use pkgbuild + productbuild
- Users see install location, usage examples, uninstall instructions,
  and must agree to Apache 2.0 license before installing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: add installer resources for macOS .pkg distribution

- Add Welcome, Read Me, License (Apache 2.0), and Distribution XML
- Fix .gitignore: scope 'machineid' rule to root only so installer/
  macos/machineid/ directory is not ignored

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: make test

* feat: concurrent Windows collection, platform tests, and CLI improvements

- Rewrite Windows collectIdentifiers to run all hardware queries
  concurrently using goroutines, reducing ID generation from ~8-12s
  to ~2-3s by parallelizing slow wmic/PowerShell calls.

- Add comprehensive platform-specific test files: windows_test.go
  (50+ tests covering parsing, fallback, concurrent collection,
  diagnostics) and linux_test.go (25+ tests covering parsing,
  validation, file reading, mock executor integration).

- Add platform-specific example files for Windows and Linux with
  testable examples for diagnostics, integrity, and platform notes.

- Improve CLI help: grouped flags by category, documented default
  behavior and exit codes, cleaner version output with aligned
  key-value pairs, rename -version.long to -version-long, include
  salt in JSON output.

- Fix all golangci-lint errors across darwin/linux/windows: add
  proper error checking in tests, nolint annotations for example
  functions, apply De Morgan's law fix.

- Update doc.go and README.md with concurrent Windows collection
  details and revised CLI documentation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* fix: handle redirect in Makefile command wrapper when MAKE_STOP_ON_ERRORS is true

Avoid double stdout redirection when the command already contains a
redirect (e.g. `> file`). Uses $(findstring) to detect existing
redirects and only adds `2>/dev/null` in that case.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chrore: update instructions

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: christiangda

.github/copilot-instructions.md

@@ -49,3 +49,15 @@ Since this is a library build in native go, the files are mostly organized follo
 - Document all exported functions, types, and variables with clear and concise comments.
 - Use examples in the documentation to illustrate how to use the library effectively.
 - Keep documentation up to date with code changes. The package documentation located at `doc.go` should provide an overview of the package and its main functionalities. and the Public documentation at `README.md` should provide an overview of the project, installation instructions, usage examples, and other relevant information.
+
+## Post-Change Checklist
+
+Prefer the Make targets that the repo already defines after making changes:
+
+```bash
+make go-fmt             # Format code
+make go-betteralign     # Align struct fields for optimal memory layout
+golangci-lint run ./... # Run linter (also checks formatting, vet, and other issues)
+make build               # Verify build
+make test                # Run tests
+```

.github/workflows/pr.yml

@@ -10,7 +10,7 @@ permissions:
   pull-requests: read
 
 jobs:
-  build:
+  test:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
@@ -94,7 +94,7 @@ jobs:
         run: |
           echo "### Test report" >> $GITHUB_STEP_SUMMARY
 
-          go test -race -coverprofile=coverage.txt -covermode=atomic -tags=unit ./... | tee -a $GITHUB_STEP_SUMMARY
+          make test | tee -a $GITHUB_STEP_SUMMARY
           echo "" >> $GITHUB_STEP_SUMMARY
 
       - name: Test coverage