fix: support text rotation in collage zone mode and respect admin set…

[flacoonb]

fix: support text rotation in collage zone mode and respect admin settings

Previously, the text rotation configured in the admin panel was ignored when
using collage layouts with zone-based text alignment (text_alignment.mode = "zone").
The zone rendering in Image::applyTextInZone() always passed rotation=0 to
imagettftext(), and Collage.php allowed JSON layout files to override the admin
rotation value.

Changes in Collage.php:

• Zone-based text alignment from layout JSON is now only applied when
  "Allow layout selection" (collageAllowSelection) is enabled. When
  disabled, admin panel coordinates (locationx, locationy, rotation)
  are used directly via legacy rendering
• Admin rotation value always takes priority over JSON layout rotation
  in both zone mode and legacy mode when layout selection is active
• text_disabled from JSON is also only honored when layout selection
  is enabled

Changes in Image.php:

• applyTextInZone() now applies the configured rotation angle to
  imagettftext() instead of hardcoding 0
• Rotated text lines are stacked perpendicular to the text direction
  using trigonometric offset calculation (sin/cos) so lines appear
  properly aligned at any angle
• Each line is individually centered along the text direction based on
  its width relative to the widest line
• The entire rotated text block is precisely centered within the text
  zone by calculating the actual bounding box of all rendered glyphs
  using imagettfbbox() with the rotation angle, then computing the
  offset needed for proper horizontal (align) and vertical (valign)
  zone alignment
• Admin line spacing (linespace) is respected as minimum distance
  between lines, preventing text from collapsing when auto-fit reduces
  the font size
• Removed outdated comment "currently only 0 supported" from
  textZoneRotation property

Closes #1433

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request? (put an "x" next to an item)

• Documentation update
• Bug fix
• New feature
• Other, please explain:

What changes did you make? (Give an overview)

When collage.allow_selection is enabled and the user selects a collage layout
with zone-based text alignment (text_alignment.mode = "zone"), the text rotation
configured in the admin panel was completely ignored. The text was always rendered
at 0 degrees regardless of the admin setting.

Root cause: Two issues:

1. Image::applyTextInZone() hardcoded rotation=0 in the imagettftext() call,
   ignoring the textZoneRotation property entirely
2. Collage.php allowed JSON layout files to override the admin rotation value
   (most layouts set rotation: 0 explicitly)

Fix:

• Admin rotation always takes priority over JSON layout rotation
• Zone-based text alignment is only applied when layout selection is enabled;
  when disabled, admin coordinates (locationx, locationy, rotation) are used directly
• applyTextInZone() now properly renders rotated text with correct line stacking
  (perpendicular to text direction using sin/cos), per-line centering along the text
  direction, and precise bounding-box-based centering within the text zone
• Admin line spacing is respected as minimum value even when auto-fit reduces font size

Is there anything you'd like reviewers to focus on?

• The rotated text rendering logic in Image::applyTextInZone(): it uses
  imagettfbbox() with the actual rotation angle to compute the precise bounding
  box of the entire text block, then centers it within the zone. This approach
  works correctly for any rotation angle (-359 to 359).
• The $c->collageAllowSelection guard on text_alignment processing in
  Collage.php: this ensures that when layout selection is disabled, the admin
  has full control over text positioning via locationx/locationy/rotation.

AI used to create this Pull Request?

Yes, Claude Code (claude-sonnet-4-6) was used to assist with:

• Analyzing the rendering pipeline to identify the root cause
• Implementing the trigonometric text positioning for rotated zone text
• Running local CI checks (PHPStan, PHPUnit, PHP Lint, pre-commit hooks)