refactor: consolidate shared modules to reduce duplication

[gupsammy]

Summary

This PR consolidates duplicated code across the extension by extracting shared modules for settings management, file helpers, and injection scripts. This improves maintainability and reduces the burden of future updates.

Changes

• Extract settings management (STORAGE_KEY, DEFAULT_SETTINGS, loadSettings, saveSettings) into a centralized settings.js module
• Extract file/path utilities (sanitizeImageFilename, generatePageSubfolder, rewriteImagePaths) into file-helpers.js
• Extract the list of content scripts to inject into injection-files.js to avoid duplication between background.js and popup.js
• Update background.js, popup.js, and lib/platform.js to use these shared modules

Commits

• b66e33b - refactor: extract injection scripts list into shared module
• 2f21d7a - refactor: extract shared settings and file helpers into modules

Files Changed

• background.js: Simplified by removing duplicated settings and file helper logic
• popup.js: Simplified by removing duplicated settings and injection script list
• lib/platform.js: Simplified by removing duplicated file helper logic
• settings.js: New centralized settings management module
• file-helpers.js: New centralized file/path utilities module
• injection-files.js: New module for shared injection scripts list

[claude]

Claude finished @gupsammy's task —— View job

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Code Review Complete ✓

Todo List

• Read all changed files
• Verify module imports and usage
• Check manifest.json for module declarations
• Look for critical/high priority issues
• Post review feedback

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Review Summary

This refactoring looks good to ship. The module consolidation is clean and doesn't introduce any functional issues.

What I Verified

✅ Module structure: All three new modules use proper IIFE patterns with redeclaration guards
✅ Import contexts: Correct loading mechanisms for each context (importScripts for service worker, script tags for popup, injection for content scripts)
✅ Injection order: file-helpers.js loads before lib/platform.js as required
✅ Backward compatibility: lib/platform.js maintains global function references
✅ No manifest changes needed: Modules are loaded contextually, not declared

Code Quality

The refactoring successfully:

• Eliminates ~46 net lines of duplicated code
• Centralizes settings management to a single source of truth
• Makes the injection script list DRY between background.js and popup.js
• Maintains all existing functionality

No critical or high-priority issues found. The code is ready to merge.

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