fix: inlineimagecontroller now has a validation check

[ARYPROGRAMMER]

This PR solves a small edge case where the Value of inlineimagecontroller used by ExtendedTextField is null. Ideally it should have some sort of error checking mechanism else when it gets saved and is played from the SavedBadges section, it throws the error:

======== Exception caught by gesture ===============================================================
The following ArgumentError was thrown while handling a gesture:
Invalid argument(s): Invalid hex string:

When the exception was thrown, this was the stack: 
#0      hexStringToBool (package:badgemagic/bademagic_module/utils/byte_array_utils.dart:35:5)
#1      SavedBadgeProvider.savedBadgeAnimation (package:badgemagic/providers/saved_badge_provider.dart:101:36)
#2      SaveBadgeCard.build.<anonymous closure>.<anonymous closure> (package:badgemagic/view/widgets/save_badge_card.dart:84:34)
#3      _InkResponseState.handleTap (package:flutter/src/material/ink_well.dart:1170:21)
#4      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:351:24)
#5      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:656:11)
#6      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:313:5)
#7      BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:283:7)
#8      GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:169:27)
#9      GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:505:20)
#10     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:481:22)
#11     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:450:11)
#12     GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:426:7)
#13     GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:389:5)
#14     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:336:7)
#15     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:305:9)
#16     _invoke1 (dart:ui/hooks.dart:328:13)
#17     PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:442:7)
#18     _dispatchPointerDataPacket (dart:ui/hooks.dart:262:31)
Handler: "onTap"
Recognizer: TapGestureRecognizer#5a747
  debugOwner: GestureDetector
  state: ready
  won arena
  finalPosition: Offset(140.7, 397.5)
  finalLocalPosition: Offset(5.7, 16.7)
  button: 1
  sent tap down

THE CHANGES IN THIS PR FIX THIS

Summary by Sourcery

Bug Fixes:

• Fixed an issue where saving a badge with an empty inline image value would throw an error.

[sourcery-ai]

Reviewer's Guide by Sourcery

This PR introduces a validation check for the inlineimagecontroller to prevent a runtime error when the value is null. A user-facing error message is now displayed if the controller value is empty, guiding the user to input a valid value before saving.

Sequence diagram for save badge validation flow

sequenceDiagram
    actor User
    participant UI as HomeScreen
    participant Controller as InlineImageController
    participant Dialog as SaveBadgeDialog

    User->>UI: Clicks Save Button
    UI->>Controller: Check text value
    alt text is empty
        Controller-->>UI: Empty value
        UI->>UI: Set error message
        UI-->>User: Display error hint
    else text has value
        Controller-->>UI: Valid value
        UI->>UI: Clear error message
        UI->>Dialog: Show save dialog
        Dialog-->>User: Display save options
    end

Loading

State diagram for inline image controller validation

stateDiagram-v2
    [*] --> Empty
    Empty --> Error: Save clicked
    Error --> Valid: Text entered
    Valid --> SaveDialog: Save clicked
    SaveDialog --> [*]

    note right of Empty: Initial state
    note right of Error: Shows red error message
    note right of Valid: Ready to save

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File-Level Changes

Change	Details	Files
Added validation for the inlineimagecontroller	A validation check is added to the onTap callback of the save button. If inlineimagecontroller.text is empty, an error message is displayed. Otherwise, the existing save dialog logic is executed. An error message is displayed using a hintText within the InputDecoration of the ExtendedTextField. The errorVal variable is introduced to manage the error message state.	lib/view/homescreen.dart

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[sourcery-ai]

Hey @ARYPROGRAMMER - I've reviewed your changes - here's some feedback:

Overall Comments:

• Consider implementing proper hex string validation instead of just checking for empty string to prevent invalid inputs from reaching hexStringToBool()
• The error message could be more specific about the expected input format (e.g., 'Please enter a valid hex string')

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟢 Testing: all looks good
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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