fix: add pandas/pyarrow as optional build dependencies for build_emails.py

Co-Authored-By: Claude Opus 4.6 <[email protected]>

pyproject.toml

@@ -14,6 +14,7 @@ dependencies = [
     "anthropic>=0.52",
     "numpy>=1.26",
     "sse-starlette>=2.0",
+    "httpx>=0.28",
 ]
 
 [project.optional-dependencies]
@@ -24,6 +25,10 @@ dev = [
     "pytest-anyio>=0.0.0",
     "scipy>=1.14",
 ]
+build = [
+    "pandas>=2.0",
+    "pyarrow>=14.0",
+]
 
 [build-system]
 requires = ["setuptools>=75"]