Fix all ty diagnostics on ifcviewer-wgpu (ci-lint ty-ios + ty-bonsai)

This branch carried v0.8.0's strict `[tool.ty.rules] all = "error"` config but
not the source fixes that were made upstream to satisfy it, so both ci-lint ty
gates were failing: `poe ty-ios` reported 256 diagnostics and `poe ty-bonsai`
258. Both are now clean.

Most fixes are ported from v0.8.0 and follow two idioms: initialise a name
before a conditional that may not bind it (plus an `assert` where the invariant
is real but not provable), and close an exhaustive `if`/`elif` chain with
`else: assert False, <discriminant>`.

The branch's own newer accessors are preserved throughout - `.file`,
`.declaration`, `file.types()`, `get_max_id()` are kept rather than reverted to
`wrapped_data.*`, and non-ty upstream changes (notably the in-progress geometry
cache removal) are deliberately not pulled in.

Notable fixes that are not straight ports:

* ifcopenshell_wrapper.pyi: `entity_instance.file` was declared as
  `def file(self) -> file`, where the property name shadows the `class file`
  below it, so the annotation resolved to `Unknown`. Every `element.file` in
  the codebase was therefore unchecked. Qualifying it to `ifcopenshell.file`
  restores `.schema` to its Literal union and surfaces no new diagnostics.

* model/wall.py: a duplicated merge fragment in the void-straddle path ran an
  always-true `if void_straddles:` that read `new_opening` from the mutually
  exclusive branch (stale value, or NameError on the first iteration), followed
  by an unreachable duplicate `elif`. Removing it makes the file match v0.8.0.

* light/operator.py: upstream's own fix unpacks three targets from two values
  and raises ValueError unconditionally; corrected to `None, None, None`.

* assign_system.py, validate.py, geom/main.py: walrus-in-genexp is valid at
  runtime (PEP 572 binds in the containing scope) but ty does not model it;
  rewritten as explicit loops, matching upstream.

Verified: poe ty-ios, poe ty-bonsai, ruff check src/ nix/, black --check .,
and compileall -W error at py3.10 (ifcopenshell-python) and py3.11 (bonsai).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/bonsai/scripts/bonsai_translations.py

@@ -216,6 +216,7 @@ def update_translations_from_po(po_directory: Path, translations_module: Path):
 
 
 if BPY_IS_LOADED:
+    import bpy
 
     class SetupTranslationUI(bpy.types.Operator):
         bl_idname = "bim.setup_translation_ui"

src/bonsai/scripts/classifications/brick_classifiction.py

@@ -82,6 +82,7 @@ class Generator:
                 }
                 """.replace("{entity}", location.split("#")[-1]))
             # filter parents for the brick entity
+            parent = None
             for row in query:
                 parent = row.get("parent").toPython()
                 if "brickschema.org" in parent and parent in references.keys():

src/bonsai/scripts/generate_furniture_library.py

@@ -1036,6 +1036,7 @@ class LibraryGenerator:
             seat_width_offset = 0.7 * width / 2 if cistern_depth else width / 2
             seat_start_width_offset = 0.6 * width
 
+            cistern_3d = None
             if cistern_height:
                 cistern = builder.rectangle(size=V(width, cistern_depth), position=shift_to_center)
                 cistern_3d = ifcopenshell.util.element.copy_deep(self.file, cistern)
@@ -1118,6 +1119,7 @@ class LibraryGenerator:
 
             # cistern
             if cistern_height:
+                assert cistern_3d
                 cistern_3d = builder.extrude(
                     cistern_3d, cistern_height + seat_level / 2, position=V(0, 0, seat_level / 2)
                 )

src/bonsai/scripts/generate_steel_profiles_library.py

@@ -143,6 +143,7 @@ class LibraryGenerator:
                     if "unused" in ifc_params:
                         del ifc_params["unused"]
 
+                    profiles_gap = ...
                     if prof_type == "profile_hollow*_square":
                         ifc_params["YDim"] = ifc_params["XDim"]
                     elif ifc_profile_name == "IfcCircleHollowProfileDef":
@@ -160,6 +161,7 @@ class LibraryGenerator:
                     profile = self.file.create_entity(ifc_profile_name, ProfileName=prof_name, ProfileType="AREA", **ifc_params)
 
                     if prof_type == "profile_l*lbeam_2l":
+                        assert profiles_gap is not ...
                         profile.ProfileName = None # to avoid name confusion
                         mode = "SLBB" if prof_name.endswith("_SLBB") else "LLBB"
                         profile = self.create_double_l_profile(profile, prof_name, profiles_gap, mode)