refactor(hashline-edit): redesign hashline format with CID-based hashing

Breaking Changes:
- Change hashline format from 'lineNum:hex|content' to 'lineNum#CID:content'
- Replace hex-based hashing (00-ff) with CID-based hashing (ZPMQVRWSNKTXJBYH nibbles)
- Simplify constants: HASH_DICT → NIBBLE_STR + HASHLINE_DICT
- Update patterns: HASHLINE_PATTERN → HASHLINE_REF_PATTERN + HASHLINE_OUTPUT_PATTERN

Benefits:
- More compact and memorable CID identifiers
- Better alignment with LSP line reference format (lineNum#ID)
- Improved error messages and diff metadata clarity
- Remove unused toHashlineContent from diff-enhancer hook

Updates:
- Refactor hash-computation for CID generation
- Update all diff-utils to use new format
- Update hook to use raw content instead of hashline format
- Update tests to match new expectations

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

src/tools/hashline-edit/index.ts

@@ -2,7 +2,7 @@ export { computeLineHash, formatHashLine, formatHashLines } from "./hash-computa
 export { parseLineRef, validateLineRef } from "./validation"
 export type { LineRef } from "./validation"
 export type { SetLine, ReplaceLines, InsertAfter, Replace, HashlineEdit } from "./types"
-export { HASH_DICT, HASHLINE_PATTERN } from "./constants"
+export { NIBBLE_STR, HASHLINE_DICT, HASHLINE_REF_PATTERN, HASHLINE_OUTPUT_PATTERN } from "./constants"
 export {
   applyHashlineEdits,
   applyInsertAfter,