Extract the shared git auth capability

[AhmadKharfan]

Why

The last feature-to-feature dependency: :feature:settings imported :feature:git's internal auth plumbing — GitAuthController, GitHubAuthDialog, GitAuthPromptState, GitAuthPromptActions and GitAuthMode.

The obvious fix would have been to export those from :feature:git:api, and it would have been wrong. Settings is not asking git to perform an operation. Both features reuse the same auth capability: git needs it when a push hits a 401, settings needs it so you can connect an account up front. Exporting one feature's internals to the other would have blessed the accidental coupling, and it would have dragged :designsystem into a contract module that is otherwise restricted to :domain.

What changed

New :core:gitauth, owning the capability both features share:

• GitAuthController — the auth state machine
• GitAuthPromptState, GitAuthPromptActions, GitAuthMode, GitHubDeviceCodeUi
• GitHubAuthDialog
• The 20 git_auth_* string resources, which had to move with the dialog
• The GitAuthController characterization tests

:feature:settings now depends on :core:gitauth and no longer on :feature:git at all. :feature:git depends on it too, as one consumer among two rather than the owner.

It is a :core: module rather than a contract module because it carries UI. That is the honest distinction: :feature:*:api modules hold contracts and may only see :domain; a capability module is shared implementation and may use the design system.

The module boundary baseline is now empty. Every feature-to-feature dependency introduced before this migration has been removed, and the check runs with zero tolerated exceptions.

Behavior

No behavior change. Code moved between modules; no logic altered.

Scope

GitHubAuthDialog's existing LongMethod and CyclomaticComplexMethod findings moved with it as baseline entries rather than being regenerated. They were already baselined in :feature:git; splitting the dialog is separate work.

Tests

• 714 tests passing, 0 failures.
• The 18 GitAuthController characterization tests moved with the controller and pass unchanged. They were written for exactly this refactor — they pin the device-flow ordering, the 1100 ms deferred close, cancellation, and the re-entrancy quirk, so this move is provably behaviour-preserving rather than merely compiling.

Verification

./gradlew test detekt verifyModuleBoundaries :app:assembleDebug — BUILD SUCCESSFUL. Boundary report: 136 dependencies checked, 0 baseline entries, 0 violations.

Verified on an emulator, with attention to the resource move, since android.nonTransitiveRClass=true means a string left behind would fail at runtime rather than at build time:

• Settings → Git & GitHub renders the account card and the Git author form
• "Sign in with GitHub" opens the dialog, and every relocated string resolves: the "Sign in to github.com" title with its host argument, the GitHub-account and access-token mode chips, the device hint, and action_cancel from :core:common
• No Resources$NotFoundException, AbstractMethodError or NoClassDefFoundError in logcat