docs: remake cycle architecture diagram in Typst and correct station numbering

[Jhawk414]

Summary

Replaces the D2 cycle architecture diagram with a high-resolution Typst/CeTZ vector diagram (docs/f404_cycle.svg and source docs/f404_cycle.typ), along with a high-res PNG artifact (docs/f404_cycle.png). Updates README.md to point to the new Typst source and removes the superseded D2 diagram source.

Key updates:

• Thermodynamic Station Numbering (SAE AS755 / ARP755): Fixes station numbering along the flowpath. Fan face is correctly designated as Station 2 (Pt2), Fan discharge as Station 2.1, Core compressor inlet as Station 2.5, HPC discharge as Station 3 (Pt3), and Nozzle entrance as Station 7. Station 1 is marked at the cowl inlet lip.
• Turbomachinery Geometries: Uses aerodynamic trapezoids for Fan, HPC, HPT, and LPT, and rounded combustion chambers for Combustor and Afterburner.
• Orthogonal Shaft Routing: Clean right-angle mechanical shaft lines dropping vertically from the bottom of each turbomachine with centered RPM labels.
• Elevated Bypass & Bleed 3: Symmetrically centered bypass duct over the core and vertical HPC Bleed 3 tap.

Related Issues

None

Backwards incompatibilities

None

New Dependencies

None (compiled SVG and PNG are checked into docs/; diagram source compiles with typst)