Add landscape page size options (#6248)

# Description of Changes

Adds orientation (portrait/landscape) to the Adjust Page Scale tool.

- Orientation as a separate parameter (per review), sent through to the
backend
- ScalePagesController simplified; PDFWithPageSize gains the orientation
field
- Regenerated tool_models.py; frontend + backend tests added

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

---------

Co-authored-by: ConnorYoh <[email protected]>

engine/src/stirling/models/tool_models.py

@@ -1094,6 +1094,15 @@ class SanitizePdfParams(ApiModel):
     remove_xmp_metadata: bool = Field(False, description="Remove XMP metadata from the PDF")
 
 
+class Orientation1(StrEnum):
+    """
+    Orientation to apply to the target page size. Ignored when pageSize is KEEP.
+    """
+
+    portrait = "PORTRAIT"
+    landscape = "LANDSCAPE"
+
+
 class PageSize(StrEnum):
     """
     The scale of pages in the output PDF. Acceptable values are A0-A6, LETTER, LEGAL, KEEP.
@@ -1112,6 +1121,10 @@ class PageSize(StrEnum):
 
 
 class ScalePagesParams(ApiModel):
+    orientation: Orientation1 = Field(
+        Orientation1.portrait,
+        description="Orientation to apply to the target page size. Ignored when pageSize is KEEP.",
+    )
     page_size: PageSize = Field(
         ..., description="The scale of pages in the output PDF. Acceptable values are A0-A6, LETTER, LEGAL, KEEP."
     )