refactor: decouple CardBrowserFragment from CardBrowser activity

[ShaanNarendran]

Purpose / Description

Finishes the decoupling for card browser fragment so it can be used outside of card browser activity.

Fixes

• For GSoC 2026: Redesign Deck Picker

Approach

Moves the remaining dependent parts into the fragment itself:

• TagsDialogFactory is created during onCreate
• useSearchView reads from prefs directly
• selectedDeckNameForUi / searchAllDecks() were moved inline and use viewModel calls
• addNoteFromCardBrowser registers it's own launcher

How Has This Been Tested?

Compiles and builds successfully.

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[david-allison]

Each commit should compile, so the test changes should be done alongside the 'test-breaking' changes to the files

[david-allison]

LGTM, assuming you tested it

[sanjaysargam]

Great going 🥳

[sanjaysargam]

Good to go. minor nitpick

[sanjaysargam]

Here we go. @ShaanNarendran you are rocking

handled