Pin z3-solver<=4.15.4.0 to fix ARM64 Docker builds

Newer z3-solver versions (4.15.8.0, 4.16.0.0) don't ship pre-built
ARM64 wheels, causing builds to fail when compiling Z3 from source.
Pin to 4.15.4.0 which was the last version with working ARM64 wheels.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: codelion

pyproject.toml

@@ -20,7 +20,7 @@ dependencies = [
     "numpy",
     "networkx",
     "openai",
-    "z3-solver",
+    "z3-solver<=4.15.4.0",
     "aiohttp",
     "flask",
     "torch",

requirements.txt

@@ -1,7 +1,7 @@
 numpy
 networkx
 openai
-z3-solver
+z3-solver<=4.15.4.0
 aiohttp
 flask
 torch

requirements_proxy_only.txt

@@ -7,6 +7,6 @@ requests
 cerebras_cloud_sdk
 numpy
 networkx
-z3-solver
+z3-solver<=4.15.4.0
 sympy
 math_verify