feat(hashline-edit): add autocorrect, BOM/CRLF normalization, and file creation support

Implements key features from oh-my-pi to improve agent editing success rates:

- Autocorrect v1: single-line merge expansion, wrapped line restoration,
  paired indent restoration (autocorrect-replacement-lines.ts)
- BOM/CRLF normalization: canonicalize on read, restore on write
  (file-text-canonicalization.ts)
- Pre-validate all hashes before mutation (edit-ordering.ts)
- File creation via append/prepend operations (new types + executor logic)
- Modular refactoring: split edit-operations.ts into focused modules
  (primitives, ordering, deduplication, diff, executor)
- Enhanced tool description with operation choice guide and recovery hints

All 50 tests pass. TypeScript clean. Build successful.

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

@@ -0,0 +1,48 @@
+import { parseLineRef } from "./validation"
+import type { HashlineEdit } from "./types"
+
+export function getEditLineNumber(edit: HashlineEdit): number {
+  switch (edit.type) {
+    case "set_line":
+      return parseLineRef(edit.line).line
+    case "replace_lines":
+      return parseLineRef(edit.end_line).line
+    case "insert_after":
+      return parseLineRef(edit.line).line
+    case "insert_before":
+      return parseLineRef(edit.line).line
+    case "insert_between":
+      return parseLineRef(edit.before_line).line
+    case "append":
+      return Number.NEGATIVE_INFINITY
+    case "prepend":
+      return Number.NEGATIVE_INFINITY
+    case "replace":
+      return Number.NEGATIVE_INFINITY
+    default:
+      return Number.POSITIVE_INFINITY
+  }
+}
+
+export function collectLineRefs(edits: HashlineEdit[]): string[] {
+  return edits.flatMap((edit) => {
+    switch (edit.type) {
+      case "set_line":
+        return [edit.line]
+      case "replace_lines":
+        return [edit.start_line, edit.end_line]
+      case "insert_after":
+        return [edit.line]
+      case "insert_before":
+        return [edit.line]
+      case "insert_between":
+        return [edit.after_line, edit.before_line]
+      case "append":
+      case "prepend":
+      case "replace":
+        return []
+      default:
+        return []
+    }
+  })
+}