Translate all 253 user-facing strings to French (formal register), including
the transfer_file_count plural. Generates values-fr/strings.xml for KMP and
fr localizations in the Apple catalog (marked needs_review).
Most strings were imported with a platform-specific `targets` (usually
apple-only) just because that's where they happen to be used today. Drop the
restriction so they default to all targets and are available to KMP too; only
the four literal `%@…` format-composition keys stay apple-only.
Also fix the placeholder parser to tolerate C length modifiers (`%lld`), and
give progress_sending_to_count a proper int arg so it emits `%1$d` on both
platforms instead of a literal `%lld`.
Replace the placeholder `context` on all 255 keys in strings.json with a
description of where each string appears and its purpose, and regenerate the
xcstrings so the comments flow through to the Apple catalog.
Add localization/ — one strings.json is the source of truth for every
user-facing string, and a Bun CLI generates the platform files:
loc migrate rebuild strings.json from existing platform files (one-time)
loc validate structural checks (plural `other`, arg refs, coverage)
loc generate emit .xcstrings (Apple) + per-language strings.xml (KMP)
Canonical `{name}` placeholders are converted to each platform's positional
printf tokens using declared arg types. Plurals use CLDR categories and emit
native forms: xcstrings plural variations and Compose <plurals> blocks.
Migration folds the KMP `transfer_file_count_one`/`_other` pair into a single
plural key, so `transferFileCountResource` now returns the plural resource and
callers resolve it with pluralStringResource.
