fix(diff): reveal a fully deleted file's hunk from an original-side search

pierreSearchRevealLine returned 0 for a fully deleted file, because it maps a deletion onto a
neighbouring new-file line and a fully deleted file has no addition lines. FileDiff.revealLine
works in 1-based new-file coordinates -- getHunkAdditionLineRange adds 1 to the side boundary, so
a +0,0 hunk is the range [1, 1), not 0. Searching Original for text in a fully deleted file
therefore never expanded that hunk in a combined diff, and selection restore hit the same path.

src/renderer/src/components/editor/pierre-diff/pierre-diff-search-view.test.ts

@@ -33,3 +33,17 @@ it('does not feed a pure-deletion line number to revealLine', () => {
   expect(revealed).toBeGreaterThanOrEqual(hunk.additionStart)
   expect(revealed).toBeLessThanOrEqual(additionEnd)
 })
+
+it('maps a fully deleted file onto the empty new-file hunk start', () => {
+  const diff = buildPierreFileDiff({
+    ...input,
+    status: 'deleted',
+    originalContent: `${'keep\n'.repeat(40)}${'drop\n'.repeat(10)}GONE\n${'keep\n'.repeat(40)}old\n`,
+    modifiedContent: ''
+  })
+  expect(diff.additionLines).toHaveLength(0)
+  expect(diff.hunks[0]?.additionStart).toBe(0)
+  expect(diff.hunks[0]?.additionCount).toBe(0)
+  // FileDiff.revealLine uses 1-based new-file ranges; +0,0 becomes [1, 1).
+  expect(pierreSearchRevealLine(diff, 51, 'deletions')).toBe(1)
+})

src/renderer/src/components/editor/pierre-diff/pierre-diff-search-view.ts

@@ -146,8 +146,8 @@ export function pierreSearchRevealLine(
   if (side === 'additions') {
     return lineNumber
   }
-  // revealLine is new-file only; never pass a pure-deletion old-file number.
-  let modifiedLine = 0
+  // revealLine is new-file only; +0,0 (fully deleted) is range [1, 1), not 0.
+  let modifiedLine = 1
   let found = false
   iterateOverDiff({
     diff,