refactor: move alignment code to linopy/alignment.py; restructure tests

doc/release_notes.rst

@@ -73,7 +73,7 @@ Most users should keep calling ``model.solve(...)``. If you want more control, y
 
 **Internal**
 
-* ``linopy.common`` provides two DataArray conversion helpers: ``as_dataarray`` (convert only) and ``broadcast_to_coords`` (convert and broadcast against ``coords``). The latter takes ``strict`` (default ``True``): any mismatch with ``coords`` raises, naming ``label`` in the error; ``strict=False`` passes mismatches through for downstream xarray alignment.
+* New module ``linopy.alignment`` owns conversion, broadcasting, and alignment of user input against coordinates (moved out of ``linopy.common``): ``as_dataarray`` (convert only), ``broadcast_to_coords`` (convert and broadcast against ``coords``; ``strict=True`` by default raises on any mismatch, naming ``label`` in the error), ``validate_alignment``, and ``align``.
 * Each ``Solver`` subclass now overrides at most three hooks: ``_build_direct`` (build the native model), ``_run_direct`` (run it), and ``_run_file`` (run the solver on an LP/MPS file). File-only solvers (CBC, GLPK, CPLEX, SCIP, Knitro, COPT, MindOpt) only override ``_run_file``.
 * New ``ConstraintLabelIndex`` cached on ``Model.constraints`` (mirrors the existing ``Variables.label_index``); ``ConstraintBase`` gains ``active_labels()`` and a ``range`` property; ``CSRConstraint`` exposes ``coords``.
 * ``linopy.common`` gains ``values_to_lookup_array``; the legacy pandas-based helpers ``series_to_lookup_array`` and ``lookup_vals`` are removed.

linopy/__init__.py

@@ -12,7 +12,7 @@
 # Note: For intercepting multiplications between xarray dataarrays, Variables and Expressions
 # we need to extend their __mul__ functions with a quick special case
 import linopy.monkey_patch_xarray  # noqa: F401
-from linopy.common import align
+from linopy.alignment import align
 from linopy.config import options
 from linopy.constants import (
     EQUAL,