refactor: split AppModule DI definitions into focused modules

[aneepal55]

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Fixes #1240 🦕

[Elforama]

Thanks for the PR! Please share a video going through the app screens to ensure nothing crashes.

[github-actions]

👋 Hi @aneepal55, thanks for the contribution!

Before this PR can be reviewed and merged, please add:

• a 🎥 screen recording / video demonstrating the change — a video is required even when there are no UI changes, to show that the parts of the app affected by this change still work
• a 🖼️ screenshot of the UI change (or mark the PR as non-ui if there is no UI change)

Just drag-and-drop the file(s) into the PR description and GitHub will upload them. This check re-runs automatically when you edit the description.

If this change has no user-visible effect, tick the "no user-visible / UI effect" box in the description (or ask a maintainer to add the non-ui label) to skip the screenshot requirement. A video is still required even with no UI changes, to show that the affected parts of the app still work.