Improvement: protect plan files from review deletion (#142)

* fix: protect plan and solution files from review/resolve deletion

The review/resolve pipeline could flag docs/plans/*.md and
docs/solutions/*.md files for deletion, contradicting /workflows:work
which treats them as living documents.

Adds protection at three layers:
- review.md: Protected Artifacts section + synthesis filter
- code-simplicity-reviewer.md: YAGNI exception for pipeline artifacts
- resolve_todo_parallel.md: Safety check to skip/wont_fix such todos

Fixes #140

* fix: protect plan and solution files from review/resolve deletion

The review/resolve pipeline could flag docs/plans/*.md and
docs/solutions/*.md files for deletion, contradicting /workflows:work
which treats them as living documents.

Adds protection at four layers:
- review.md: Protected Artifacts section and synthesis filter
- code-simplicity-reviewer.md: YAGNI exception for pipeline artifacts
- resolve_todo_parallel.md: Skip and wont_fix todos targeting these paths
- git-history-analyzer.md: Note not to characterize them as unnecessary

Fixes #140

---------

Co-authored-by: Axl Ottle <axl@Axls-Virtual-Machine.local>

plugins/compound-engineering/commands/resolve_todo_parallel.md

@@ -12,6 +12,8 @@ Resolve all TODO comments using parallel processing.
 
 Get all unresolved TODOs from the /todos/\*.md directory
 
+If any todo recommends deleting, removing, or gitignoring files in `docs/plans/` or `docs/solutions/`, skip it and mark it as `wont_fix`. These are compound-engineering pipeline artifacts that are intentional and permanent.
+
 ### 2. Plan
 
 Create a TodoWrite list of all unresolved items grouped by type.Make sure to look at dependencies that might occur and prioritize the ones needed by others. For example, if you need to change a name, you must wait to do the others. Output a mermaid flow diagram showing how we can do this. Can we do everything in parallel? Do we need to do one first that leads to others in parallel? I'll put the to-dos in the mermaid diagram flow‑wise so the agent knows how to proceed in order.