feat(schema-engine): add Rich Text Editor field type (#5308)

[XananasX7]

Summary

Implements the rich text editing capability requested in #5308.

Closes #5308

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Changes

New component — RichTextEditorComponent

Location: frontend/src/app/modules/schema-engine/rich-text-editor/

A self-contained Angular component that uses the browser's native contenteditable + execCommand API — no new npm dependencies.

Toolbar capabilities:

Button	Action
B	Bold
I	Italic
U̲	Underline
List icon	Bullet list
Ordered list icon	Numbered list
H1 / H2 / H3	Headings
🔗	Insert hyperlink (inline dialog, auto-prepends https://)

Key design decisions:

• Implements ControlValueAccessor → works with [formControl] bindings already in schema-form.component with zero glue code
• Stores/emits HTML strings so formatted content round-trips through the VC document without data loss
• Backward-compatible: existing plain-text values display correctly (plain text is valid HTML)
• readonly input disables editing and hides the toolbar

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schema-form.component (edit mode)

• Added isRichText(item) helper (returns true when customType === 'richText')
• isInput() now excludes richText to prevent double-rendering
• <app-rich-text-editor> rendered for both single-value and array-item rich-text fields

schema-form-view.component (read-only display)

• Added isRichText(item) helper; isInput() excludes richText
• Rich-text values rendered via [innerHTML] inside a styled .rte-view-content div so formatting is visible in the final output view

FieldTypesDictionary (interfaces package)

Added new entry:

{ name: 'Rich Text', type: 'string', format: undefined, pattern: undefined, isRef: false, customType: 'richText' }

This makes Rich Text selectable as a field type in the schema configuration UI.

generate-document.ts (interfaces package)

Added richText case so dry-run document generation works for schemas that contain rich-text fields.

schema-engine.module.ts

• Declared RichTextEditorComponent
• Added ReactiveFormsModule to imports

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Acceptance criteria (per #5308)

Criterion	Status
Bold, italic, underline	✅
Bulleted and numbered lists	✅
Headings / subheadings (H1–H3)	✅
Hyperlinks	✅
Formatting preserved in final output	✅ (HTML stored as field value)
Existing plain-text entries unaffected	✅ (plain text renders as HTML)
Unit / UI tests confirm functionality	✅ (15 spec cases in rich-text-editor.component.spec.ts)
No external dependencies added	✅

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Test coverage (rich-text-editor.component.spec.ts)

• Component creation
• Toolbar visible / hidden based on readonly
• writeValue sets editor content correctly
• null writeValue treated as empty
• onChange callback called on input
• onTouched callback called on blur
• isEmpty edge cases (empty, whitespace-only HTML, text content)
• setDisabledState properly sets flag
• Link dialog open/cancel/insert flows
• Protocol auto-prepend for bare domains
• All required toolbar actions present