feat: introduced hashline API redesign with structured operations and LINE#ID format

- Redesigned hashline edit API with new operation names (set, set_range, insert) and structured body parameter accepting string arrays for multiline edits.
- Changed hashline reference format from LINE:HASH to LINE#ID throughout tools and documentation for improved clarity.
- Enhanced insert operation to support optional before/after anchors enabling flexible insertion positioning and boundary echo stripping.
- Made hashline autocorrect heuristics conditional on PI_HL_AUTOCORRECT environment variable for controlled behavior.
- Added benchmark reports for claude-haiku-4-5 and GPT-5.2-Codex models demonstrating hashline edit variant performance.

.omp/skills/system-prompts/SKILL.md

@@ -379,7 +379,6 @@ Output final answer after ####.
 When using: 3-5 diverse examples covering edge cases.
 
 ```xml
-<examples>
 <example name="simple">
 Input: X
 Output: Y
@@ -389,7 +388,6 @@ Output: Y
 Input: X'
 Output: Y'
 </example>
-</examples>
 ```
 
 ### Long Context Handling