Fix internal bridges over Hilbert Curve / Octagram Spiral sparse infill

[aceRage]

Description

Port of OrcaSlicer/OrcaSlicer#15206 (open, mergeable) into Snapmaker-Ultra.

Internal bridges over Hilbert Curve and Octagram Spiral sparse infill could be generated mid-air because determine_bridging_angle() sampled every local turning direction, then applied a blind Hilbert/Octagram offset. This port:

• Uses the supporting (lower) layer's rotation template + 90°, plus model alignment, for Hilbert/Octagram bridge angles
• Keeps real sparse-infill anchors instead of replacing them
• Samples curved bridge boundaries at 4× resolution (scan_spacing)
• Sets params.extrusion_role on the anchoring fill path so plane-path origins match make_fills()

Ultra-specific adaptations

• calculate_infill_rotation_angle already existed in Fill/Fill.cpp and is export-only via Fill.hpp. It is not duplicated.
• Ultra's Fill.hpp is the thin Filler wrapper; the helper is declared there so PrintObject.cpp can share the same rotation grammar as infill generation.
• generate_sparse_infill_polylines_for_anchoring did not set extrusion_role; that is now wired like make_fills().
• Ultra has no relative_bridge_angle, sparse_infill_smooth_factor, or separated_infills. Those Orca keys were not introduced.
• Ultra still has an active 3D Honeycomb / Cross Hatch fixed-angle fallback. That behavior is preserved at the call site (Orca had already commented it out of the helper).
• Tests use Ultra's init_print(..., config, comments) signature (no nullptr slicer argument).

Paint-depth paths are untouched. Unrelated bridge_over_infill logic outside the PR hunks is unchanged.

Screenshots/Recordings/Graphs

See upstream PR screenshots: OrcaSlicer#15206

Tests

Ported/adapted from Orca#15206:

• Sparse plane-path anchors match the printed infill — Hilbert / Octagram / Archimedean, multiline, rotation
• Internal bridge angles follow the lower infill layer and model rotation
• Turning infill does not replace the anchors of another region

Cloud compile limits: this environment cannot build the full slicer / fff_print_tests binary. Please run locally after deps are available:

cmake --build build --target fff_print_tests --parallel
./build/tests/fff_print/fff_print_tests "[InternalBridge]" --order rand --warn NoAssertions