Implement Collections feature for grouping related prompts, instructions, and chat modes (#232)

* Initial plan

* Implement core Collections feature with YAML parsing and README generation

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* Complete Collections feature implementation with validation, tooling, and documentation

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* Update generated README files to include collections instructions

* Fix YAML parsing logic bug: replace impossible condition with proper indentation check

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* Refactor: Extract YAML parser to shared module and improve user experience

Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>

* fixing task and file permissions

* Better args handling

* Adding some more collections

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: aaronpowell <434140+aaronpowell@users.noreply.github.com>
Co-authored-by: Aaron Powell <me@aaron-powell.com>

collections/TEMPLATE.md

@@ -0,0 +1,81 @@
+# Collections Template
+
+Use this template to create a new collection of related prompts, instructions, and chat modes.
+
+## Basic Template
+
+```yaml
+id: my-collection-id
+name: My Collection Name
+description: A brief description of what this collection provides and who should use it.
+tags: [tag1, tag2, tag3] # Optional discovery tags
+items:
+  - path: prompts/my-prompt.prompt.md
+    kind: prompt
+  - path: instructions/my-instructions.instructions.md  
+    kind: instruction
+  - path: chatmodes/my-chatmode.chatmode.md
+    kind: chat-mode
+display:
+  ordering: alpha # or "manual" to preserve order above
+  show_badge: false # set to true to show collection badge
+```
+
+## Field Descriptions
+
+- **id**: Unique identifier using lowercase letters, numbers, and hyphens only
+- **name**: Display name for the collection
+- **description**: Brief explanation of the collection's purpose (1-500 characters)
+- **tags**: Optional array of discovery tags (max 10, each 1-30 characters)
+- **items**: Array of items in the collection (1-50 items)
+  - **path**: Relative path from repository root to the file
+  - **kind**: Must be `prompt`, `instruction`, or `chat-mode`
+- **display**: Optional display settings
+  - **ordering**: `alpha` (alphabetical) or `manual` (preserve order)
+  - **show_badge**: Show collection badge on items (true/false)
+
+## Creating a New Collection
+
+### Using VS Code Tasks
+1. Press `Ctrl+Shift+P` (or `Cmd+Shift+P` on Mac)
+2. Type "Tasks: Run Task"
+3. Select "create-collection"
+4. Enter your collection ID when prompted
+
+### Using Command Line
+```bash
+node create-collection.js my-collection-id
+```
+
+### Manual Creation
+1. Create `collections/my-collection-id.collection.yml`
+2. Use the template above as starting point
+3. Add your items and customize settings
+4. Run `node validate-collections.js` to validate
+5. Run `node update-readme.js` to generate documentation
+
+## Validation
+
+Collections are automatically validated to ensure:
+- Required fields are present and valid
+- File paths exist and match the item kind
+- IDs are unique across collections
+- Tags and display settings follow the schema
+
+Run validation manually:
+```bash
+node validate-collections.js
+```
+
+## File Organization
+
+Collections don't require reorganizing existing files. Items can be located anywhere in the repository as long as the paths are correct in the manifest.
+
+## Best Practices
+
+1. **Meaningful Collections**: Group items that work well together for a specific workflow or use case
+2. **Clear Naming**: Use descriptive names and IDs that reflect the collection's purpose
+3. **Good Descriptions**: Explain who should use the collection and what benefit it provides
+4. **Relevant Tags**: Add discovery tags that help users find related collections
+5. **Reasonable Size**: Keep collections focused - typically 3-10 items work well
+6. **Test Items**: Ensure all referenced files exist and are functional before adding to a collection