feat: add 15 auto-test functions + destroy-test + versioning rules

Batch 1: ok, echo, error, cpu, slow
Batch 2: jsonout, recurse, bigdata, math, timestamp
Batch 3: multiline, encoding, nested, memory, chain
Tests: create, update (code_hash), idempotency, destroy, re-create
All 15 functions verified via curl with JWT auth

examples/auto-funcs/code/math/main.py

@@ -0,0 +1,12 @@
+import math
+
+def main():
+    results = {
+        "pi": round(math.pi, 10),
+        "e": round(math.e, 10),
+        "sqrt2": round(math.sqrt(2), 10),
+        "factorial20": math.factorial(20),
+        "log1000": round(math.log(1000), 10),
+    }
+    parts = [f"{k}={v}" for k, v in results.items()]
+    return "; ".join(parts)