fix(auth): stop dropping the user identifier from localized sign-in labels

[demolaf]

55 locales declared fui_signed_in_as without the %1$s that the base string and DefaultAuthUIStringProvider both expect, so the user identifier was silently dropped and those users saw a bare "Signed in as" with nobody named. Every locale now carries the argument, positioned where that language puts it rather than simply appended.

The rest of the change clears the localization lint findings that needed no translator, taking auth/lint-baseline.xml from 168 entries to 43. Literal ... becomes an ellipsis character in the base strings, which the locale files already used; one of those strings also carried a format specifier, and that pairing is what crashed TypographyDetector on lint's first run here, so fixing the text removes the trigger rather than baselining around it. The Romance locales that require a CLDR many plural get one, derived from each file's own other text. The 14 AuthException messages that ship empty are marked translatable="false", because they are override hooks that fall back to the Firebase SDK message and so have no source text to translate. PluralsCandidate is suppressed with tools:ignore on the four declarations that trigger it rather than disabled for the module, since minimumPasswordLength is an unbounded Int and "at least 1 characters long" is reachable, so the check still needs to guard every other string. AppBundleLocaleChanges is suppressed at the one construct it describes, because the bundle configuration and any Play Core dependency belong to the app that embeds this library.

What stays baselined is 43 MissingTranslation findings, real UI copy that the Compose rewrite added and never sent for translation across 50 languages. No repo-side edit clears those, so the baseline can only be deleted once translations land.

---

Maintainer note: Fixes internal CPRN-432

[gemini-code-assist]

Code Review

This pull request configures and integrates Android Lint checks across modules, introducing a repo-wide lintAll task, updating the CI build script, and documenting the linting policy. It also includes various bug fixes and optimizations, such as optimizing QR code generation to reduce JNI crossings, refining coroutine cancellation in AuthFlowController, updating localized strings with proper placeholders, and adding nullability annotations in the paging source. Feedback suggests explicitly validating the non-null Query parameter in DatabasePagingSource using Objects.requireNonNull to prevent potential null pointer exceptions.