Cherry-pick of #16820 to RC4.0.2_master

Purpose

Issue: WalkDirectoryTree in StartPage.xaml.cs adds directory entries even if they contain no .dyn files. It filters .dyn files, but directories are added before checking for children.

This PR improves the sample file directory traversal logic by filtering out dependency folders and empty directories from the sample file tree.

Key Changes:
Adds filtering to exclude directories ending with ".dependencies" from the sample file tree
Implements empty directory filtering by only adding directories that contain .dyn files (directly or in subdirectories)

Summary

Added filtering to exclude .dyn files with "Generative Design" as the active linter.

Changes Made

JSON Handling

• Added using Newtonsoft.Json.Linq; to handle JObject instances from JSON deserialization.

New Method: IsGenerativeDesignFile (lines 603–680)

• Checks if the file is a .dyn or .dyf file
• Deserializes the JSON and looks for the Linting property (case-insensitive)
• Handles both JObject and Dictionary<string, object> cases
• Extracts the activeLinter value
• Returns true if it equals "Generative Design" (case-insensitive)
• Includes error handling

Integration into File Processing (lines 254–258)

• Skips files that have Generative Design as the active linter before adding them to the sample files list

Home Page Filtering Behavior

The home page now filters out:

• Non-.dyn files
• Directories ending in .dependencies
• Directories that don't contain .dyn files
• .dyn files with "Generative Design" as the active linter

After Fix:

Declarations

Check these if you believe they are true

• Is documented according to the standards
• The level of testing this PR includes is appropriate
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.

Release Notes

• Samples section in Home no longer shows results from .dependencies folders (Generative Design samples) or blank directories.

Reviewers

@DynamoDS/eidos

FYIs

@emru-y