Fix hashline-edit deduplication and validation

- Canonicalize anchors in dedupe keys to handle whitespace variants
- Make lines field required in edit operations
- Only allow unanchored append/prepend to create missing files
- Reorder delete/rename validation to prevent edge cases
- Add allow_non_gpt_model and max_prompt_tokens to config schema
  ```

src/tools/hashline-edit/validation.ts

@@ -15,7 +15,7 @@ const MISMATCH_CONTEXT = 2
 
 const LINE_REF_EXTRACT_PATTERN = /([0-9]+#[ZPMQVRWSNKTXJBYH]{2})/
 
-function normalizeLineRef(ref: string): string {
+export function normalizeLineRef(ref: string): string {
   const originalTrimmed = ref.trim()
   let trimmed = originalTrimmed
   trimmed = trimmed.replace(/^(?:>>>|[+-])\s*/, "")