docs(pcb): add PCBWay fabrication support #63

Problem

Tiny Engineer currently documents and supports PCB fabrication primarily through JLCPCB.

This makes the fabrication workflow less convenient for contributors who prefer or already use PCBWay. Even when the design files themselves are compatible, differences in fabrication requirements, Gerber handling, drill files, BOM/CPL expectations, assembly options, and ordering flow can make the process unclear.

Proposed change

Add PCBWay as a documented and tested alternative PCB fabrication path alongside JLCPCB.

The work should include:

• verify that the current PCB design can be fabricated by PCBWay without design changes
• prepare and validate the Gerber and drill package expected by PCBWay
• document the recommended PCBWay fabrication settings
• verify layer stack, board thickness, copper weight, solder mask, surface finish, and other relevant manufacturing options
• prepare and validate BOM and pick-and-place / CPL files for PCBWay assembly where applicable
• document any rotation, footprint, polarity, or component-mapping differences compared with the current JLCPCB workflow
• place at least one test order and verify the manufactured / assembled boards
• add step-by-step PCBWay ordering instructions to the PCB fabrication documentation

JLCPCB should remain supported. PCBWay should be added as an alternative, with any provider-specific differences clearly documented.