feat: skip mobile ship all/staged choice on a clean tree

[leynier]

Summary

Mobile Ship always showed All Changes / Staged Changes. Desktop #727 ships staged without that choice when git status has no entries, which is how already-committed work opens a PR.

The phone now calls mobile.git.status on the workspace root (empty relativeRoot), matching desktop and host Ship. A clean tree hides the segmented control and ships staged. Uncommitted changes keep All vs Staged. A missing or failed status keeps the choice.

No new runtime verb. Auto-branch of unpushed main stays on the host.

Validation

• flutter test test/pull_request_ship_sheet_test.dart test/pull_request_actions_test.dart with Flutter 3.47.2
• flutter analyze on the touched files

Risks

• Status is a fresh workspace-root git.status at Ship time. A nested Source Control root is ignored on purpose, because host Ship always plans against workspace.path.
• Hosts without source control still show All/Staged, because status cannot be read.

[pullfrog]

Important

Ship hides All vs Staged from the Source Control panel snapshot. That snapshot can be a nested repository, while the host always ships the workspace root.

Reviewed changes

This PR ports desktop's clean-tree Ship skip to mobile: hide All vs Staged when git status has no entries, and submit stagedOnly: true.

• Scope helper — shipShowsWorkingTreeScopeChoice hides the control only for a loaded snapshot with empty entries; a missing or failed status keeps All vs Staged.
• Ship sheet — askWorkingTreeScope (default true) gates the segmented control and, when false, initializes _stagedOnly so submit still ships staged.
• Panel wiring — ship awaits _askWorkingTreeScope before opening the sheet, reading sourceControlControllerProvider when the host advertises Source Control.
• Tests — helper, sheet, and panel coverage for clean, dirty, and failed status; no nested-root case.
• Docs — mobile/AGENTS.md Ship bullet records the hide-when-clean behavior.

  ^{｜ Fix all ➔ ｜ Fix 👍s ➔ ｜ View workflow run ｜ Using Grok ｜ 𝕏}

[pullfrog]

✅ No new issues found.

Reviewed changes

Since the prior review, Ship decides All vs Staged from workspace-root git status, matching desktop and host plan_ship.

• Workspace-root status — _askWorkingTreeScope now calls gitStatus(workspaceId) with empty relativeRoot and no longer reads the Source Control controller.
• Nested-root coverage — a panel test keeps All vs Staged when a saved nested root would have been clean and the workspace is dirty.
• Docs — mobile/AGENTS.md records that the hide uses workspace-root status.

  ^{｜ View workflow run ｜ Using Grok ｜ 𝕏}