[PM-37318] chore: Standardize premium upgrade alert titles to "Premium subscription required"

[KatherineInCode]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-37318

📔 Objective

Two "Upgrade to Premium" alert dialogs used feature-specific titles ("Archive unavailable", "Attachments unavailable") instead of the standard title shared by other premium alerts. This updates both to use "Premium subscription required" for consistency, and removes the two now-unused localization string keys.

[github-actions]

🤖 Bitwarden Claude Code Review

Overall Assessment: APPROVE

This tech-debt PR standardizes two premium upgrade alert titles ("Archive unavailable" and "Attachments unavailable") to use the existing shared premiumSubscriptionRequired localization, and removes the two now-unused English string keys. All call sites and their unit tests (AlertVaultTests, VaultListProcessorTests, VaultItemActionHelperTests) were updated consistently. The unrelated // swiftlint:disable file_length removal in KeyConnectorServiceTests.swift is safe — that file is 398 lines, under the 400-line warning threshold.

Code Review Details

No findings. Verified that the remaining archiveUnavailable/attachmentsUnavailable references are Swift factory method names (intentionally unchanged) rather than the removed localization keys, and that PremiumSubscriptionRequired exists in the English source. The old keys remaining in non-English .strings files is expected behavior reconciled by the translation tooling.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.56%. Comparing base (0185de5) to head (639c233).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2803      +/-   ##
==========================================
- Coverage   80.83%   78.56%   -2.27%     
==========================================
  Files        1018     1141     +123     
  Lines       64903    72199    +7296     
==========================================
+ Hits        52463    56724    +4261     
- Misses      12440    15475    +3035     

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