refactor(packages): extract hashline-core package

Move the hash-anchored edit core (hash computation, validation, edit operations, text normalization, chunk formatter, diff utilities, and a runtime-aware xxHash32 binding) into a new @oh-my-opencode/hashline-core workspace package.

The src/tools/hashline-edit/ surface becomes a set of thin re-export shims, so existing import paths in the plugin keep working while the pure logic lives behind a stable package boundary that has no opencode runtime dependencies.

Tests: bun test packages/hashline-core src/tools/hashline-edit

src/tools/hashline-edit/edit-ordering.ts

@@ -1,56 +1 @@
-import { parseLineRef } from "./validation"
-import type { HashlineEdit } from "./types"
-
-export function getEditLineNumber(edit: HashlineEdit): number {
-  switch (edit.op) {
-    case "replace":
-      return parseLineRef(edit.end ?? edit.pos).line
-    case "append":
-      return edit.pos ? parseLineRef(edit.pos).line : Number.NEGATIVE_INFINITY
-    case "prepend":
-      return edit.pos ? parseLineRef(edit.pos).line : Number.NEGATIVE_INFINITY
-    default:
-      return Number.POSITIVE_INFINITY
-  }
-}
-
-export function collectLineRefs(edits: HashlineEdit[]): string[] {
-  return edits.flatMap((edit) => {
-    switch (edit.op) {
-      case "replace":
-        return edit.end ? [edit.pos, edit.end] : [edit.pos]
-      case "append":
-      case "prepend":
-        return edit.pos ? [edit.pos] : []
-      default:
-        return []
-    }
-  })
-}
-
-export function detectOverlappingRanges(edits: HashlineEdit[]): string | null {
-  const ranges: { start: number; end: number; idx: number }[] = []
-  for (let i = 0; i < edits.length; i++) {
-    const edit = edits[i]
-    if (edit.op !== "replace" || !edit.end) continue
-    const start = parseLineRef(edit.pos).line
-    const end = parseLineRef(edit.end).line
-    ranges.push({ start, end, idx: i })
-  }
-  if (ranges.length < 2) return null
-
-  ranges.sort((a, b) => a.start - b.start || a.end - b.end)
-  for (let i = 1; i < ranges.length; i++) {
-    const prev = ranges[i - 1]
-    const curr = ranges[i]
-    if (curr.start <= prev.end) {
-      return (
-        `Overlapping range edits detected: ` +
-        `edit ${prev.idx + 1} (lines ${prev.start}-${prev.end}) overlaps with ` +
-        `edit ${curr.idx + 1} (lines ${curr.start}-${curr.end}). ` +
-        `Use pos-only replace for single-line edits.`
-      )
-    }
-  }
-  return null
-}
+export { getEditLineNumber, collectLineRefs, detectOverlappingRanges } from "@oh-my-opencode/hashline-core"