[DBA-303] bump demo-snowflake-project deps to stable versions (#93)

Switch from pinned dev versions to compatible-release specifiers:
- databao: ==0.3.4.dev1 -> ~=0.3.4
- databao-agent: ==0.2.1.dev12 -> ~=0.2.1
- databao-context-engine[snowflake]: ==0.7.1.dev2 -> ~=0.7.2

Refresh uv.lock accordingly.

Author: catstrike

examples/demo-snowflake-project/pyproject.toml

@@ -5,9 +5,9 @@ description = "Databao demo project for Snowflake"
 readme = "README.md"
 requires-python = ">=3.11,<3.12"
 dependencies = [
-    "databao==0.3.4.dev1",
-    "databao-agent==0.2.1.dev12",
-    "databao-context-engine[snowflake]==0.7.1.dev2",
+    "databao~=0.3.4",
+    "databao-agent~=0.2.1",
+    "databao-context-engine[snowflake]~=0.7.2",
     "streamlit[snowflake]>=1.53.0",
     "adbc-driver-snowflake>=1.10.0",
     "adbc-driver-manager>=1.10.0",