Format all YAML files to pass yamllint validation

- Added document start markers (---) to all YAML files
- Fixed line length issues by breaking long lines appropriately
- Removed trailing whitespace throughout all files
- Added proper newlines at end of files
- Fixed truthy value format ('on' -> 'on')
- Standardized YAML formatting across workflows and issue templates
- Used multi-line strings (>) for long descriptions
- Maintained readability while adhering to 80-character line limit

All YAML files now pass yamllint validation with only minor warnings remaining.

.github/ISSUE_TEMPLATE/config.yml

@@ -1,3 +1,4 @@
+---
 blank_issues_enabled: false
 contact_links:
   - name: GitHub Discussions
@@ -8,4 +9,4 @@ contact_links:
     about: Read our Code of Conduct and community standards
   - name: Contributing Guide
     url: https://github.com/wshobson/agents/blob/main/.github/CONTRIBUTING.md
-    about: Learn how to contribute effectively to this project
+    about: Learn how to contribute effectively to this project