chore: consolidate agent instructions into .claude/CLAUDE.md (#1855)

Author: sbryngelson

.claude/CLAUDE.md

@@ -0,0 +1,15 @@
+* New branches cannot be made on MFlowCode/MFC, they are made on forks
+* PRs:
+    * made using AI tools like Claude Code and Codex should say so. 
+    * are made from those MFC forks
+    * that change CFD result need verification PR is correct
+    * follow template
+    * that break a feature but promise a followup PR to fix it are rejected
+* Commands:
+    * MFC should almost always build and run using the ./mfc.sh command
+    * Running mfc.sh commands can create a lock file in build/ that is sticky, be careful
+* Programming and Design:
+    * New code should follow the DRY principle and also make side-effect code DRY as well
+    * Comments should be as short as possible without sacrificing value
+    * GPU macros should follow existing the source's GPU macro principles and patterns
+    * Functions/subroutines/modules shorter is better while being correctness, fast, and separating concerns 

.claude/rules/common-pitfalls.md

@@ -206,7 +206,7 @@ jobs:
 
             Hard scope rules:
             - Do NOT inspect checked-out repository code except:
-              - ./CLAUDE.md
+              - ./.claude/CLAUDE.md
               - ./.claude/rules/*.md (max 10 files)
               - ${{ steps.review_input.outputs.review_diff_path }}
               - ${{ steps.review_input.outputs.changed_files_path }}
@@ -225,7 +225,7 @@ jobs:
 
             Allowed workflow:
             1) ls -1 .claude/rules 2>/dev/null || true
-            2) cat CLAUDE.md 2>/dev/null || true
+            2) cat .claude/CLAUDE.md 2>/dev/null || true
             3) find .claude/rules -maxdepth 1 -name "*.md" -print | head -n 10 | xargs -I{} cat "{}" 2>/dev/null || true
             4) cat "${{ steps.review_input.outputs.changed_files_path }}"
             5) cat "${{ steps.review_input.outputs.review_diff_path }}"
@@ -238,7 +238,7 @@ jobs:
             - Do NOT restate the full PR summary.
             - If there are no high-confidence findings, leave .claude-review/output.md empty and STOP.
 
-            Review standard (in priority order per CLAUDE.md "Code Review Priorities"):
+            Review standard (in priority order):
             1. Correctness (logic bugs, numerical issues, array bounds)
             2. Precision discipline (stp vs wp mixing)
             3. Memory management (@:ALLOCATE/@:DEALLOCATE pairing, GPU pointer setup)

.github/workflows/claude-code-review.yml

@@ -0,0 +1 @@
+.claude/CLAUDE.md