[Task Editor] Improve rendering performance

[rfontanarosa]

closes #2247

• trackBy to prevent angular from destroying and recreating DOM nodes on every change
• Lifted expanded state from each TaskFormComponent instance up to TaskEditorComponent as a signal
• ChangeDetectionStrategy.OnPush on TaskFormComponent and TaskConditionFormComponent so they only re-render when their inputs actually change
• input() + effect() replacing @input() tasks + ngOnChanges in TaskEditorComponent, so the form is only rebuilt when the tasks signal changes — not on every input
  change
• TaskOptionsPipe made pure to avoid re-evaluation on every change detection cycle

[codecov-commenter]

Codecov Report

❌ Patch coverage is 50.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.38%. Comparing base (48817b2) to head (ab64490).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...onents/shared/task-editor/task-editor.component.ts	60.00%	6 Missing ⚠️
...hared/task-editor/task-form/task-form.component.ts	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2462      +/-   ##
==========================================
+ Coverage   59.32%   59.38%   +0.05%     
==========================================
  Files         113      113              
  Lines        2793     2797       +4     
  Branches      422      421       -1     
==========================================
+ Hits         1657     1661       +4     
  Misses       1074     1074              
  Partials       62       62              

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