Add safe native PR checks and explicit Swift scanning

[hideouts-io]

Adds an always-emitted native build, plist/signature/architecture validation, and explicit Swift plus Actions CodeQL analysis. The scan build has a read-only token; SARIF upload runs separately through pinned Actions. Adds repository instructions and weekly Actions dependency updates.

Local source build, plist, strict signature, and arm64 verification passed. Hosted CI does not launch the app, install helpers, modify launchd, or enforce network policy. Privileged runtime behavior requires separate local integration validation. GitHub source analysis at the PR revision remains the completion gate.

[github-advanced-security]

You are seeing this message because GitHub Code Scanning has recently been set up for this repository, or this pull request contains the workflow file for the Code Scanning tool.

What Enabling Code Scanning Means:

• The 'Security' tab will display more code scanning analysis results (e.g., for the default branch).
• Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results.
• You will be able to see the analysis results for the pull request's branch on this overview once the scans have completed and the checks have passed.

For more information about GitHub Code Scanning, check out the documentation.