Switch project to uv and add sticky-header scroll to dashboard table

Adds pyproject.toml, uv.lock, .python-version, and a .gitignore for uv
package management. Constrains the dashboard table to the viewport
height with a sticky thead so column headers remain visible while
scrolling.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

pyproject.toml

@@ -0,0 +1,11 @@
+[project]
+name = "css-test"
+version = "0.1.0"
+description = "Add your description here"
+readme = "README.md"
+requires-python = ">=3.13"
+dependencies = [
+    "fastapi>=0.136.0",
+    "pydantic>=2.13.3",
+    "uvicorn[standard]>=0.45.0",
+]