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.

docs/finance/total-investment.md

@@ -21,7 +21,7 @@ July 2026; the underlying THB estimates are unchanged, because EUR/THB at
 | Galvanics line (Digital Matrix) | 320k – 650k | 10.7M – 21.4M | six-figure-USD turnkey inference from vendor research |
 | Zero-discharge water treatment (ZLD) | 90k – 240k | 3.0M – 8.0M | utilities CSV option row |
 | Stamper prep (Sibert VSP, VSF, VSC) | 60k – 170k | 1.9M – 5.7M | estimate, pricing unpublished |
-| Mastering and cutting room (Agnew lathe and head, cutter amps, console, room treatment) | 290k – 580k | 9.6M – 19.1M | estimate, bespoke market |
+| Mastering and cutting room (Agnew or Sillitoe lathe system, cutter amps, console, room treatment) | 290k – 580k | 9.6M – 19.1M | estimate, bespoke market; the Sillitoe SDMS lists at USD 125k for lathe, head, amplifier and automation (ex tax, shipping), which makes the low end reachable; band kept until both quotes exist |
 | Metrology and QC stack (confocal, profiler, XRF, inline vision, audio station) | 350k – 810k | 11.5M – 26.7M | estimate, phaseable |
 | Utilities, solar, HVAC, racking baseline | 730k – 1,270k | 24.0M – 41.6M | reviewed [utilities CSV](utilities-investment.csv), THB-native |
 | Building ~1,500 m² plus civil works | 650k – 1,100k | 21.4M – 36.2M | estimate at 12,000–20,000 THB/m² Thai industrial construction plus ~20% site works |