Refactor: Migrate DI imports from javax.inject to jakarta.inject

## Description

The project currently depends on `jakarta.inject:jakarta.inject-api:2.0.1` (Jakarta EE), but the codebase still uses `javax.inject.*` imports throughout, which is incompatible with the declared dependency.

## Context

- Raised in PR #4069: https://github.com/cryptomator/cryptomator/pull/4069#discussion_r2592297190
- Affects 20+ files across the codebase
- Related Dagger migration issue: https://github.com/google/dagger/issues/2058

## Task

Update all `javax.inject.*` imports to `jakarta.inject.*` across the codebase to align with the Jakarta EE dependency.

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Requested by: @infeo