fix: remove arbitrary 100-line limit from codebase mapping

The limit was causing loss of useful context, especially code examples
in TESTING.md and CONVENTIONS.md. Document quality > arbitrary brevity.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

get-shit-done/workflows/execute-phase.md

@@ -1177,7 +1177,6 @@ For each document needing update:
 1. Read current document
 2. Identify what changed (new entries, removed entries, modified sections)
 3. Apply minimal edits to reflect new state
-4. Keep document under 100 lines (summarize if needed)
 
 **Commit codebase updates:**
 ```bash