tests/fixtures: the ownership contract says exact-match, not truthy

Round 10 review, finding 6. The cross-repo contract still documented carrier
1 as "any value other than false/0 is truthy" after R10-4 made pixelpass
match it exactly. A future producer following the fixture could emit "true"
and silently lose the carrier.

Committed byte-identical with pixelpass's copy in the same session, as the
file's own rules require.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/fixtures/ownership-tag-contract.txt

@@ -20,9 +20,17 @@
 # PipeWire registry `global` event and readable only via a node bind, so the
 # primary taint root must not rest on one observation mechanism alone.
 
-# Carrier 1 — a node property. The consumer treats any value other than
-# "false"/"0" as truthy, which is the fail-closed direction; the producer
-# always emits exactly this value.
+# Carrier 1 — a node property, matched EXACTLY: `prop_value` below is the
+# ONLY spelling the consumer reads as owned. A producer emitting "true", "yes"
+# or "" is NOT owned on this carrier, and only carrier 2 would still catch it.
+#
+# ⚠️ This wording is load-bearing and it CHANGED in round 10. The consumer
+# used to accept any value other than "false"/"0", on the theory that leniency
+# over-excludes and is therefore safe. It is not: leniency buys false-positive
+# exclusion, and it let any process suppress a rival application's audio from
+# the share with a property it did not even have to spell right. Fail-closed
+# on this feature is about ANCESTRY — an unresolvable graph is not eligible —
+# not about parsing.
 prop_key=peerspeak.owned
 prop_value=1