fix(zemax): correct unit handling and folded-system geometry in importer

[beneaze]

Summary

Several long-standing correctness issues in the Zemax -> component-editor import. The integration worked structurally but the semantics were off in several places. This PR reworks parsing and conversion, and adds a synthetic .zmx fixture so the previously-skipped parser/converter tests run on every PR.

Parser

• UNIT card parsed. MM | CM | M | IN are normalised to mm at parse time: DISZ/DIAM/ENPD are multiplied by the scale; CURV is divided. Previously inch-unit files were silently treated as mm and imported 25.4x too small.
• DIAM is a semi-diameter, not a full diameter. Field renamed diameter -> semi_diameter_mm; the converter no longer divides by two again. A 1 in achromat (DIAM 12.7) now imports as a 25.4 mm-tall component, not 12.7 mm.
• PARM N value parsed. Length-valued PARMs on COORDBRK surfaces are UNIT-scaled. New is_mirror / is_coordinate_break / is_aspheric helpers on ZemaxSurface.

Converter

• 2D frame (pos_x, pos_y, angle_rad) replaces the previous cumulative_x + direction scalar. Each interface line is placed perpendicular to the current propagation direction.
• COORDBRK rotates / translates the frame: PARM 1 = decenter perpendicular to current axis, PARM 4 = in-plane tilt about y. Out-of-plane PARMs (2/3/5) cannot be represented in 2D and are dropped.
• GLAS MIRROR emits element_type=mirror; angle_rad += pi after a planar reflection. Multi-mirror systems (for example, periscopes with two non-parallel folds) now unfold correctly.
• EVENASPH / ODDASPHE are approximated as spheres at their base radius and annotated with (Asphere approx.). A warning is added to component notes + log service.
• STOP annotation: a stop surface that survives the dummy filter gets (Aperture Stop) appended to its name.
• Image surface (last) and flat air-to-air dummies are dropped: no more ghost interfaces cluttering the import.
• COMM no longer overwrites the auto-generated name. It is prefixed instead, so part numbers and material/curvature info both survive.
• Dead sag block removed: the renderer already derives sag from radius_of_curvature_mm.

Examples

examples/zemax_parse_simple.py is now a 75-line thin wrapper over the canonical ZemaxParser + ZemaxToInterfaceConverter. It previously had its own 263-line inline parser with the same DIAM-as-full-diameter bug, perpetuating the misconception.

Tests

• tests/fixtures/sample.zmx: synthetic AC254-100-B-shaped prescription so the parser/converter tests run on every PR (they were universally skipped before because no fixture was checked in).
• New coverage in test_zemax_import.py:
  • TestUnitParsing - mm/cm/in/unknown scaling, including end-to-end conversion of an inch-unit prescription
  • TestMirrorHandling - GLAS MIRROR -> mirror element, direction flip, curved mirror
  • TestSurfaceFiltering - image plane skipped, dummy air-to-air dropped, flat refractives kept
  • TestNamePreservation - COMM preserved alongside auto-generated descriptive name
  • TestCoordinateBreak - PARM parsing with UNIT scaling, in-plane tilt rotates next interface, perpendicular decenter shifts vertex
  • TestPeriscope - two 45 degree fold mirrors leave the optical axis parallel to entry but offset in y
  • TestAsphereAnnotation, TestStopAnnotation, TestMirrorFlag
• test_zemax_converter.py: dropped stale interfaces_v2 / kind references that were preventing the fixture-driven tests from running.
• UI-level smoke coverage now exercises the Component Editor Zemax import path with the checked-in .zmx fixture.

Test count: 15 active -> 56 active.

Test plan

• pytest tests/services/test_zemax_converter.py tests/services/test_zemax_parser.py tests/services/test_zemax_import.py - 56 pass
• python examples/zemax_parse_simple.py tests/fixtures/sample.zmx - prints the expected component summary (1 in achromat, 25.4 mm full aperture, 3 interfaces with right radii / material progression)
• Adjacent service tests (test_paths_red, test_linked_assembly_service, test_storage_service) still pass
• uv run --extra dev pytest tests/ui/test_component_editor.py::test_component_editor_imports_zemax_fixture -q
• uv run --extra dev ruff check tests/ui/test_component_editor.py
• Local real-file smoke: ZemaxImporter.import_file() with Thorlabs LA1131-A.zmx from the local vendor catalog imports LA1131-A N-BK7 Plano-Convex Lens as 2 interfaces with 50.8 mm aperture

Out of scope (deliberately)

• Out-of-plane PARMs on COORDBRK (y-decenter, tilt-about-x, tilt-about-z): the editor is 2D.
• Aspheric coefficients beyond the base radius.
• Inline Tilt/Decenter group cards on STANDARD surfaces (legacy alternative to COORDBRK). Modern Zemax files use COORDBRK.

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