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/tool-description.ts

@@ -7,14 +7,14 @@ WORKFLOW:
 4. Use anchors as "LINE#ID" only (never include trailing ":content").
 
 VALIDATION:
-- Payload shape: { "filePath": string, "edits": [...], "delete"?: boolean, "rename"?: string }
-- Each edit must be one of: set_line, replace_lines, insert_after, insert_before, insert_between, replace
-- text/new_text must contain plain replacement text only (no LINE#ID prefixes, no diff + markers)
+ Payload shape: { "filePath": string, "edits": [...], "delete"?: boolean, "rename"?: string }
+ Each edit must be one of: set_line, replace_lines, insert_after, insert_before, insert_between, replace, append, prepend
+ text/new_text must contain plain replacement text only (no LINE#ID prefixes, no diff + markers)
 
 LINE#ID FORMAT (CRITICAL - READ CAREFULLY):
 Each line reference must be in "LINE#ID" format where:
-- LINE: 1-based line number
-- ID: Two CID letters from the set ZPMQVRWSNKTXJBYH
+ LINE: 1-based line number
+ ID: Two CID letters from the set ZPMQVRWSNKTXJBYH
 
 OPERATION TYPES:
 1. set_line
@@ -25,10 +25,34 @@ OPERATION TYPES:
 6. replace
 
 FILE MODES:
-- delete=true deletes file and requires edits=[] with no rename
-- rename moves final content to a new path and removes old path
+ delete=true deletes file and requires edits=[] with no rename
+ rename moves final content to a new path and removes old path
 
 CONTENT FORMAT:
-- text/new_text can be a string (single line) or string[] (multi-line, preferred).
-- If you pass a multi-line string, it is split by real newline characters.
-- Literal "\\n" is preserved as text.`
+ text/new_text can be a string (single line) or string[] (multi-line, preferred).
+ If you pass a multi-line string, it is split by real newline characters.
+ Literal "\\n" is preserved as text.
+
+FILE CREATION:
+ append: adds content at EOF. If file does not exist, creates it.
+ prepend: adds content at BOF. If file does not exist, creates it.
+ CRITICAL: append/prepend are the ONLY operations that work without an existing file.
+
+OPERATION CHOICE:
+ One line wrong \u2192 set_line
+ Block rewrite \u2192 replace_lines
+ New content between known anchors \u2192 insert_between (safest \u2014 dual-anchor pinning)
+ New content at boundary \u2192 insert_after or insert_before
+ New file or EOF/BOF addition \u2192 append or prepend
+ No LINE#ID available \u2192 replace (last resort)
+
+AUTOCORRECT (built-in \u2014 you do NOT need to handle these):
+ Merged lines are auto-expanded back to original line count.
+ Indentation is auto-restored from original lines.
+ BOM and CRLF line endings are preserved automatically.
+ Hashline prefixes and diff markers in text are auto-stripped.
+
+RECOVERY (when >>> mismatch error appears):
+ Copy the updated LINE#ID tags shown in the error output directly.
+ Re-read only if the needed tags are missing from the error snippet.
+ ALWAYS batch all edits for one file in a single call.`