Vendor crabrl-fork source and remove submodule linkage

- Replace `rust/crabrl-fork` gitlink with tracked source files
- Add workspace notes documenting why the fork is vendored
- Update ignore rules for vendored fork build artifacts

rust/crabrl-fork/benchmarks/compare.py

@@ -0,0 +1,71 @@
+#!/usr/bin/env python3
+"""
+Compare crabrl performance with Arelle
+"""
+
+import subprocess
+import time
+import sys
+from pathlib import Path
+
+def run_crabrl(filepath):
+    """Run crabrl and measure time"""
+    cmd = ["../target/release/crabrl", "parse", filepath]
+    start = time.perf_counter()
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    elapsed = (time.perf_counter() - start) * 1000
+    
+    if result.returncode == 0:
+        # Parse output for fact count
+        facts = 0
+        for line in result.stdout.split('\n'):
+            if 'Facts:' in line:
+                facts = int(line.split(':')[1].strip())
+                break
+        return elapsed, facts
+    return None, 0
+
+def run_arelle(filepath):
+    """Run Arelle and measure time"""
+    try:
+        cmd = ["python3", "-m", "arelle.CntlrCmdLine", 
+               "--file", filepath, "--skipDTS", "--logLevel", "ERROR"]
+        start = time.perf_counter()
+        result = subprocess.run(cmd, capture_output=True, text=True, timeout=30)
+        elapsed = (time.perf_counter() - start) * 1000
+        
+        if result.returncode == 0:
+            return elapsed
+        return None
+    except:
+        return None
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: compare.py <xbrl-file>")
+        sys.exit(1)
+    
+    filepath = sys.argv[1]
+    print(f"Comparing performance on: {filepath}\n")
+    
+    # Run crabrl
+    crabrl_time, facts = run_crabrl(filepath)
+    if crabrl_time:
+        print(f"crabrl: {crabrl_time:.1f}ms ({facts} facts)")
+    else:
+        print("crabrl: Failed")
+    
+    # Run Arelle
+    arelle_time = run_arelle(filepath)
+    if arelle_time:
+        print(f"Arelle: {arelle_time:.1f}ms")
+    else:
+        print("Arelle: Failed or not installed")
+    
+    # Calculate speedup
+    if crabrl_time and arelle_time:
+        speedup = arelle_time / crabrl_time
+        print(f"\nSpeedup: {speedup:.1f}x faster")
+
+if __name__ == "__main__":
+    main()