[5.2] Fix media manager invalid filename

[STUDYHUB02]

Pull Request for Issue #45087 .

Summary of Changes

1. Added an early validation check to detect and block filenames that contain the '$' character.
2. Updated the language file to include a new language string (COM_MEDIA_ERROR_INVALID_FILENAME) that provides a clear error message when disallowed characters are detected.
3. These changes ensure that any attempt to rename a file with invalid characters is explicitly rejected, avoiding silent sanitization and user confusion.

Testing Instructions

1. Open the Media Manager in Joomla.
2. Test Case 1: Attempt to rename a file using a name composed solely of invalid symbols (e.g., $$$).
   Expected: The operation should immediately fail with the error “Invalid file name.”
3. Test Case 2: Attempt to rename a file using a name that includes both valid characters and '$' (e.g., abc$$).
   Expected: The operation should be blocked with the same error message, ensuring consistent handling.
4. Verify that renaming files without any '$' characters works as expected.

Actual result BEFORE applying this Pull Request

1. When a file is renamed using a name that consists solely of invalid symbols (e.g., $$$), Joomla displays an error indicating that the file name cannot be made safe.
2. When the file name includes both valid characters and '$' symbols (e.g., abc$$), Joomla silently strips the '$' symbols and renames the file, showing a success message.
3. This inconsistent behavior can confuse users about what is allowed and what is not.

Expected result AFTER applying this Pull Request

1. Any attempt to rename a file with a name that contains the '$' character—whether the name is composed solely of '$'
   symbols or mixed with valid characters—will be uniformly blocked.
2. Users will see a single, clear error message: “Invalid file name.”
3. This change provides a consistent and clear user experience regarding filename validations in the Media Manager.

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[imejine]

I have tested this item 🔴 unsuccessfully on 44e5e47

Tested with mixed results;

https://snipboard.io/bofT4D.jpg

After patch, file is not renamed (success), but the error shown is not the expected string/message (fail).

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[SumCompanyInc]

I have tested this item 🔴 unsuccessfully on 44e5e47

i will say that the filename handling tested successfully, however the language en-GB did not seem to pull the right language translation. it showed the language key token, "COM_MEDIA_ERROR_INVALID_FILENAME" instead of, "Invalid file name."

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45141.}

[Agapiiii]

The patch Is successful in getting error when renaming a file/folder with a special symbol, but it displays an incorrect error message

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45141.}

[Agapiiii]

https://ibb.co/VWDB3D4j

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/45141.}