fix(i18n): add quantity-aware plural resources

[A-EDev]

Summary

• Converts 40 live count-bearing English string resources to Android plurals so singular and plural quantities render correctly.
• Updates Compose and non-Compose call sites to use quantity-aware resource APIs.
• Removes 16 confirmed-unused string resources.
• Removes conflicting localized string definitions for the converted resource names; affected locales fall back to the English plural resources until plural translations are added.

Related issue

Not linked to an issue.

Change type

• Bug fix
• Feature
• Refactor or maintenance
• Build, packaging, or CI
• Documentation

Validation

• ./gradlew :app:assembleGithubDebug
• ./gradlew :app:testGithubDebugUnitTest
• I ran any additional flavor-specific build or test tasks affected by this change.
• I manually tested the affected behavior on an Android device or emulator.

Additional checks:

• ./gradlew ktlintCheck
• ./gradlew :app:compileFossDebugKotlin
• git diff --check

All listed automated checks passed after merging the latest main branch. Device testing was not performed; this PR is ready for GitHub CI and review testing.

Test device and Android version: Not applicable (not manually tested).

Risk and compatibility

Low implementation risk. The change only affects string-resource types and quantity-aware lookups. It does not change the database, preferences, permissions, dependencies, networking, playback, background work, or telemetry. Locales without matching plural resources temporarily use the default English plural text instead of retaining incompatible same-name string resources.

• The change does not introduce secrets, private data, or unexpected telemetry.
• New user-facing text uses Android string resources.
• Dependency and lockfile changes are intentional and limited to this PR (none changed).
• Room schema changes include the required version bump and migration, or this PR does not change the Room schema.
• Breaking changes and upgrade steps are clearly documented (none expected).

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