feat: upgrade agentex-sdk from 0.4.18 to 0.9.4

Supersedes PR #155. Key changes:
- agentex-sdk 0.4.18 → 0.9.4
- Adds [tool.uv] environments for linux + darwin to ensure the
  lockfile includes platform-specific wheels for both (claude-agent-sdk
  only publishes per-platform wheels: 0.1.48 for Linux, 0.1.49 for macOS)
- Lockfile regenerated with all new transitive deps

Note: fastapi remains pinned at <0.116 by agentex-sdk, so starlette
CVE-2025-62727 is still blocked. Requires an agentex-sdk release
that relaxes the fastapi upper bound.

Build + runtime tested: base, dev, docs-builder, and production stages
all pass on linux/arm64 (Docker on Apple Silicon).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: scale-ballen

pyproject.toml

@@ -6,7 +6,7 @@ authors = [{ name = "Felix Su", email = "felix.su@scale.com" }]
 readme = "README.md"
 requires-python = ">=3.12,<3.13"
 dependencies = [
-    "agentex-sdk==0.4.18",
+    "agentex-sdk==0.9.4",
     "temporalio>=1.18.0",
 ]
 
@@ -20,6 +20,12 @@ docs = [
     "agentex[docs]",
 ]
 
+[tool.uv]
+environments = [
+    "sys_platform == 'linux'",
+    "sys_platform == 'darwin'",
+]
+
 [tool.uv.workspace]
 members = ["agentex"]