feat: Implement review all diff against main, including everything

[nimrodkor]

Generated description

Below is a concise technical summary of the changes proposed in this PR:
Surface the correct diff context when reviewing local changes by enhancing LocalDiffPrompt, the repo git helpers, and the broader review flow state to carry branch comparison data. Update LocalPullRequestReview and the PR selector UI so the local review action only appears with actual changes and the walkthrough titles describe the branch vs default comparison.

Topic	Details
Review context	Highlight branch-versus-base context in the UI during local reviews and update status messaging to reflect what is being reviewed. Modified files (2) src/flows/LocalReview/LocalPullRequestReview.tsx src/flows/Review/Review.tsx Latest Contributors(2) User Commit Date nimrod@baz.co feat: Add support for ... April 13, 2026 yuvalyacoby feat: Full pr data imp... December 09, 2025
Diff detection	Orchestrate branch-aware diff detection so local review flows can compare the current branch to the default base when available and fall back to uncommitted changes otherwise. Modified files (4) src/flows/LocalReview/LocalDiffPrompt.tsx src/lib/git.ts src/pages/PRSelector/PullRequestSelector.tsx src/pages/PRSelector/PullRequestSelectorContainer.tsx Latest Contributors(2) User Commit Date nimrod@baz.co feat: Add support for ... April 13, 2026 yuvalyacoby feat: Ready to merge (... December 28, 2025

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