Add the Sillitoe SDMS as a second mastering lathe candidate

Sillitoe Audio Technology (Australia) sells a complete cutting system:
lathe, MMFB feedback cutterhead, cutting amplifier, Space / Time Control
automation with a virtual groove, vacuum and microscope, at a published
USD 125,000 ex tax and shipping. Vendor landscape gets the narrative and
an Agnew-or-Sillitoe comparison; supplier map, total investment basis,
roadmap item 13 and the digital factory's no-telemetry section (STC cue
sheet, Open Groove export, stylus hours) follow.

README.md

@@ -61,7 +61,9 @@ The detail lives in dedicated documents:
   50/50 automated/semi-automatic fleet strategy, the Newbilt system under
   evaluation (~USD 232k quoted scope), and site requirements
 - [Vendor landscape](docs/suppliers/vendor-landscape.md): researched
-  candidates for mastering and cutting (Agnew Analog), galvanics equipment
+  candidates for mastering and cutting (Agnew Analog, and the Sillitoe
+  SDMS with integrated cutting automation at a published USD 125k),
+  galvanics equipment
   (Plating Power / Digital Matrix), stamper preparation (Sibert), bridge
   stamper service (Stamper Discs), and automated presses (Pheenix Alpha)
 - [Equipment needs and supplier map](docs/suppliers/equipment-suppliers.md):