Add workflow template publishing feature to collaborative editor

[midigofrank]

Description

Implement UI and backend integration for publishing workflows as templates and updating existing templates. This feature is restricted to superusers and requires workflows to be saved before publishing.

Frontend changes:

• Add TemplatePublishPanel component with form for name, description, and tags
• Add TextAreaField form component with tag management UI
• Add publish/update template button to CodeViewPanel
• Integrate workflow_template state into SessionContextStore
• Add template_updated channel listener
• Add useWorkflowTemplate hook for accessing template data
• Show button state based on unsaved changes and user permissions

Backend integration:

• Connect to publish_template channel request
• Send YAML workflow code and positions to backend
• Handle template_updated messages from server
• Support both create and update operations

Test updates:

• Add workflow_template field to session context mocks
• Mock useUser, useWorkflowTemplate, and useURLState in CodeViewPanel tests
• Update all session context factory functions with template support

Closes #3921

Validation steps

1. Ensure you are a support user
2. Open the Workflow settings -> Then workflow YAML
3. You should find a button to publish template

AI Usage

Please disclose how you've used AI in this work (it's cool, we just want to know!):

• Code generation (copilot but not intellisense)
• Learning or fact checking
• Strategy / design
• Optimisation / refactoring
• Translation / spellchecking / doc gen
• Other
• I have not used AI

You can read more details in our Responsible AI Policy

Pre-submission checklist

• I have performed a self-review of my code.
• I have implemented and tested all related authorization policies. (e.g., :owner, :admin, :editor, :viewer)
• I have updated the changelog.
• I have ticked a box in "AI usage" in this PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.83%. Comparing base (3964acb) to head (cde67f8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3994   +/-   ##
=======================================
  Coverage   88.82%   88.83%           
=======================================
  Files         422      422           
  Lines       19069    19085   +16     
=======================================
+ Hits        16938    16954   +16     
  Misses       2131     2131           

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