[WIP] Implement edit tool for surgical file edits

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Implement edit tool for surgical file edits</issue_title>
<issue_description>Priority: P1 (required for Rook autonomy)

Spec:

• Accept parameters: {path, old_string, new_string, replace_all?}
• Read file → find old_string → replace with new_string → write back
• Validate uniqueness of old_string to prevent ambiguous edits (unless replace_all=true)
• Error if old_string not found or multiple matches without replace_all
• Reference implementation: OpenClaw's edit tool

Files:

• Create src/tools/edit.ts
• Register in tool registry
• Add JSON Schema definition

Tests:

• Unit tests for unique/multiple match cases
• Integration test with agent loop

Acceptance:

• Tool executes via agent loop
• Handles edge cases (file not found, ambiguous match)
• Rook can perform surgical edits without overwriting entire files

Ref: gap-analysis-report.md P1-1</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Implement edit tool for surgical file edits #122

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