Record the Making Vinyl feedback on traceability

Most people the team talked to in Haarlem were strongly interested in the
full-traceability approach. For Sibert it was one of the reasons to talk to
us at all; without it their representative would strongly advise against
the plan, and seeing buildfor.life's development and data work convinced
him the project comes from the right direction.

Exhibitor briefing gets an "After the show" section (feedback, what has
been filed since); traceability.md opens with the market signal; roadmap
item 1 notes it as supply-side evidence, with buyer prices still missing;
README project status updated (show attended, Payap lead).

README.md

@@ -42,13 +42,20 @@ steps are open planning items.
 
 ## Project Status
 
-**Planning stage** (as of mid-2026).
+**Planning stage** (as of October 2026).
 
 - Industry outreach has been ongoing for several years: equipment vendors,
   material suppliers, and independent consultants.
-- Alexander and Simona will soon travel to
-  [Making Vinyl](https://makingvinyl.com/) in Haarlem, Netherlands, to gather
-  further insights from the pressing industry.
+- Alexander and Simona attended
+  [Making Vinyl Europe 2026](https://makingvinyl.com/) in Haarlem (30
+  September to 2 October). Most people they talked to were strongly
+  interested in the full-traceability approach, and for Sibert it was a
+  reason to engage at all (notes in the
+  [exhibitor briefing](docs/suppliers/making-vinyl-europe-2026-exhibitors.md#after-the-show)).
+- Payap University (Chiang Mai) has offered land on lease and wants to
+  build joint student programmes with the plant
+  ([site candidates](docs/site-candidates.md),
+  [Payap partnership](docs/payap-partnership.md)).
 - A collaboration with [ResurRec](https://www.resurrec.com/) is under
   discussion.