Add test that __version__ matches pyproject.toml's version

`solisdash.__version__` in `src/solisdash/__init__.py` and the
`[project].version` field in `pyproject.toml` are two hand-edited
sources of truth that have to stay in sync for `uv build` and the
installed package's `__version__` to agree.

This session twice hit the failure mode where a worktree's
`pyproject.toml` got bumped but `__init__.py` was missed (or vice
versa). The new test reads `pyproject.toml` and asserts equality —
fails loudly the next time it happens.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jdrumgoole

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "solisdash"
-version = "0.2.3"
+version = "0.2.4"
 description = "Self-hosted dashboard for the SolisCloud platform"
 readme = "README.md"
 requires-python = ">=3.12"

src/solisdash/__init__.py

@@ -1 +1 @@
-__version__ = "0.2.3"
+__version__ = "0.2.4"

tests/test_smoke.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import tomllib
+from pathlib import Path
+
 from fastapi.testclient import TestClient
 
 import solisdash
@@ -9,6 +12,15 @@ def test_package_version() -> None:
     assert solisdash.__version__
 
 
+def test_version_matches_pyproject() -> None:
+    """`__version__` and `pyproject.toml [project].version` are two hand-kept
+    sources of truth — drift here means a release bumps one but not the other.
+    """
+    pyproject = Path(__file__).parent.parent / "pyproject.toml"
+    data = tomllib.loads(pyproject.read_text())
+    assert solisdash.__version__ == data["project"]["version"]
+
+
 def test_health(client: TestClient) -> None:
     response = client.get("/health")
     assert response.status_code == 200