Refactor permission variable names (#3457)

## Refactor: Improve clarity of permission variable names

Renamed confusing `can[Action]` boolean variables to `prevent[Action]`
(e.g., `canPrint` -> `preventPrinting`) in `PasswordController.java`,
`AddPasswordRequest.java`, and `add-password.html`.


The previous `can[Action]` convention was misleading, as `true` meant
the action was *disallowed*. The new `prevent[Action]` naming directly
reflects the intent (`true` = prevented), improving code clarity.

**Changes:**

*   Updated variable names in controller logic
*   Updated `@Schema` descriptions in `AddPasswordRequest.java`
* Updated corresponding HTML element attributes (`id`, `name`, `for`) in
`add-password.html`

**Important Notes:**

* The underlying logic still inverts the boolean when setting
permissions (e.g., `AccessPermission.setCanPrint(!preventPrinting)`).
* User-facing UI text remains unchanged per request of @Frooodle in
#3420.

**Why not invert the API logic**
*   Inverting API (to can[action] logic) would either invalidate the UI
* Inverting API AND changing UI would warrant bigger translation effort
to change it in all languages
* This version is consistent (meaning what the UI says is actually done)
and preserve the UI language (meaning no translations needed) however it
is inconsistent with PDFBox methods naming scheme

**PDFBox**

* **PDFBox Interaction:** This refactor addresses the naming *within*
Stirling-PDF's API and Front-end layers only. The controller logic
intentionally inverts the `prevent[Action]` boolean
(`ap.setCanPrint(!preventPrinting)`) to correctly interact with the
underlying PDFBox methods. No further renaming related to these
permissions is necessary as the PDFBox methods themselves retain the
`can[Action]` names.


Underlying logic is not changed so it should work but just in case I
tested locally on an Adobe PDF that contained form in Chrome.



## New variable names in API

![new API variable
names](https://github.com/user-attachments/assets/f3d56aaf-0455-4f65-af14-c1a07a02d11a)

**Related Issues:**

Closes #3427
Closes #3420

---

## Checklist

### General

- [x] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [x] 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/HowToAddNewLanguage.md)
(if applicable)
- [x] I have performed a self-review of my own code
- [x] 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/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### 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)

- [x] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#6-testing)
for more details.

src/main/java/stirling/software/SPDF/model/api/security/AddPasswordRequest.java

@@ -29,31 +29,29 @@ public class AddPasswordRequest extends PDFFile {
             defaultValue = "256")
     private int keyLength = 256;
 
-    @Schema(description = "Whether the document assembly is allowed", example = "false")
-    private boolean canAssembleDocument;
+    @Schema(description = "Whether document assembly is prevented", example = "false")
+    private boolean preventAssembly;
+
+    @Schema(description = "Whether content extraction is prevented", example = "false")
+    private boolean preventExtractContent;
 
     @Schema(
-            description = "Whether content extraction for accessibility is allowed",
+            description = "Whether content extraction for accessibility is prevented",
             example = "false")
-    private boolean canExtractContent;
+    private boolean preventExtractForAccessibility;
 
-    @Schema(
-            description = "Whether content extraction for accessibility is allowed",
-            example = "false")
-    private boolean canExtractForAccessibility;
+    @Schema(description = "Whether form filling is prevented", example = "false")
+    private boolean preventFillInForm;
 
-    @Schema(description = "Whether form filling is allowed", example = "false")
-    private boolean canFillInForm;
+    @Schema(description = "Whether document modification is prevented", example = "false")
+    private boolean preventModify;
 
-    @Schema(description = "Whether the document modification is allowed", example = "false")
-    private boolean canModify;
+    @Schema(description = "Whether modification of annotations is prevented", example = "false")
+    private boolean preventModifyAnnotations;
 
-    @Schema(description = "Whether modification of annotations is allowed", example = "false")
-    private boolean canModifyAnnotations;
+    @Schema(description = "Whether printing of the document is prevented", example = "false")
+    private boolean preventPrinting;
 
-    @Schema(description = "Whether printing of the document is allowed", example = "false")
-    private boolean canPrint;
-
-    @Schema(description = "Whether faithful printing is allowed", example = "false")
-    private boolean canPrintFaithful;
+    @Schema(description = "Whether faithful printing is prevented", example = "false")
+    private boolean preventPrintingFaithful;
 }