Pass the correct lines to the discussion reply box

What does this MR do and why?

This is part 2 of a 3-part change. The uses the new action introduced in part 1 to get the correct line range to provide to the discussion reply box.

Part	Purpose	MR
1	Add diffs store action implementation	!202439 (merged)
2	Pass comment lines range to the reply box	👈🏻 You are here
3	Pass comment lines range to the comment edit interface	!202711 (merged)

References

• For #557266 (closed)

Screenshots or screen recordings

Before	After
Screencast_from_2025-08-22_20-33-43	Screencast_from_2025-08-22_20-29-04

How to set up and validate locally

1. Have a multi-line comment
2. Click in the input field to reply to the comment
3. Click the "Insert suggestion" button

MR acceptance checklist

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