Lite: add support for moving commits below branches

[OliverJAsh]

Related: GB-1735

[Copilot]

Pull request overview

Adds Lite workspace support for moving commits below branch rows by enriching operation resolution with HeadInfoIndex so “below branch” can resolve to the bottom of the branch’s segment rather than the branch ref itself.

Changes:

• Extend getOperations/getOperation with an optional operation context (headInfoIndex) and use it to enable “move below branch”.
• Update workspace UI call sites to compute/pass headInfoIndex when determining available operations (navigation filtering, drag/drop, keyboard controls, dry-run labels).
• Implement branch “below” RelativeTo resolution via segmentBottomRelativeTo(...) using headInfoIndex branch context.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
apps/lite/ui/src/routes/project/$id/workspace/WorkspacePage.tsx	Builds headInfoIndex and uses it when filtering outline items by available operations in transfer mode.
apps/lite/ui/src/routes/project/$id/workspace/OutlineTree/OutlineTree.tsx	Passes headInfoIndex into dry-run operation lookup so “below branch” operations can be surfaced consistently.
apps/lite/ui/src/routes/project/$id/workspace/OperationTarget.tsx	Derives headInfoIndex via query select and uses it for drag/drop operation availability and tooltip labeling.
apps/lite/ui/src/routes/project/$id/workspace/OperationControls.tsx	Uses headInfoIndex when computing keyboard transfer operations.
apps/lite/ui/src/operations/operation.ts	Introduces optional operation context and enables “below branch” by resolving to the bottom of the branch’s segment.