Fix wheel and sdist build configuration (#377)

## Summary

Build artifacts is broken after switching from `hatch` to `uv`: the
wheel is coming out empty, and the sdist is unpacked into a `src/`
directory instead of a clean project layout.

Split the Hatch config into per-target sections:
- `[tool.hatch.build.targets.wheel]` — sets `packages =
["src/databricks"]` so the `databricks.labs.blueprint` package is
actually included in the wheel.
- `[tool.hatch.build.targets.sdist]` — uses `only-include = ["src",
"README.md", "LICENSE", "NOTICE"]` so the sdist contains the source tree
and metadata at the top level.

## Test plan
- [x] `uv build` produces a non-empty wheel containing
`databricks/labs/blueprint/...`
- [x] sdist unpacks with `src/`, `README.md`, `LICENSE`, `NOTICE` at the
top level
- [x] `pip install` the wheel in a fresh venv and `import
databricks.labs.blueprint` succeeds

---------

Co-authored-by: Andrew Snare <andrew.snare@databricks.com>

Author: mwojtyczka

pyproject.toml

@@ -66,9 +66,20 @@ requires = [
 ]
 build-backend = "hatchling.build"
 
-[tool.hatch.build]
-sources = ["src"]
-include = ["src"]
+[tool.hatch.build.targets.sdist]
+only-include = [
+    "/.build-constraints.txt",
+    "/README.*",
+    "/LICEN[CS]E",
+    "/NOTICE",
+    "/pyproject.toml",
+    "/src/",
+    "/tests/",
+    "/uv.lock",
+]
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/databricks"]
 
 [tool.hatch.version]
 path = "src/databricks/labs/blueprint/__about__.py"