Improve file forwarding rules, clean Gallery picker, and handle garbage messages in Group Chat

[girishjadhav-cosmica]

Description:
This MR addresses three improvements across the application to enhance user experience and maintain expected behavior:

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1. File Forwarding Restriction

• Prevent forwarding a file to its original owner.
• Added validation to block this action.
• Ensured proper user feedback is shown when the action is not allowed.
• Done tests to verify this restriction.
  closes Prevent forwarding a file to its original owner #73

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2. Gallery Picker Cleanup

• Removed unnecessary "Gallery" and "Audio" options from the Gallery picker.
• Improved UI clarity by showing only relevant options.
• Verified that existing functionality is not affected.
  closes Remove "Gallery" and "Audio" options from Gallery #74

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3. Group Chat Garbage Messages Handling

• Replaced garbage or invalid messages with a fallback text: "Privitty Message".
• Improved message rendering for better readability.
• Added proper test coverage and verified behavior across scenarios.
  closes Replace garbage messages in Group Chat with "Privitty Message" #75

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Changes:

• Added validation logic for forwarding restriction.
• Updated UI for Gallery picker.
• Implemented fallback handling for invalid chat messages.
• Added and updated tests for all three changes.

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Testing:

• Verified files cannot be forwarded to their original owner.
• Confirmed forwarding works for valid recipients.
• Checked that "Gallery" and "Audio" options are removed from the picker.
• Ensured garbage messages are replaced with "Privitty Message".
• All tests are passing and no regressions observed.

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Impact:

• Improves system integrity and prevents incorrect actions.
• Enhances UI clarity and user experience.
• Ensures clean and consistent chat behavior.

[nyerunkar]

Approved