fix(ci): replace uvicorn[standard] with explicit extras for cross-build

uvicorn[standard] pulls uvloop via a 'sys_platform != win32' marker.
pip evaluates env markers against the HOST (Linux in CI), so uvloop
is requested even in a --platform win_amd64 resolve. No uvloop wheel
exists for Windows, so pip backtracks across every uvicorn[standard]
version and fails with ResolutionImpossible.

Use plain uvicorn plus the Windows-compatible extras we actually need
(httptools, websockets, python-dotenv).

build-dist-windows.sh

@@ -40,9 +40,18 @@ echo '..\app' >> "$PTH_FILE"
 echo "Downloading Windows wheels..."
 
 # Core dependencies
+# NOTE: uvicorn[standard] pulls in uvloop via `sys_platform != 'win32'` marker.
+# pip evaluates env markers against the HOST (Linux in CI), so uvloop is
+# requested, but `--platform win_amd64 --only-binary :all:` cannot find a
+# Windows wheel for uvloop (none exist). Result: pip backtracks across every
+# uvicorn[standard] version and ResolutionImpossible. Fix: use plain uvicorn
+# and list only the Windows-compatible standard extras we actually need.
 CORE_DEPS=(
     "fastapi>=0.109.0"
-    "uvicorn[standard]>=0.27.0"
+    "uvicorn>=0.27.0"
+    "httptools>=0.5.0"
+    "websockets>=10.4"
+    "python-dotenv>=0.13"
     "pydantic>=2.0"
     "pydantic-settings>=2.0"
     "pyyaml>=6.0"