host/observer: tag the live prop-recovery row with the real wire value

Verification-round follow-up to 1b01847. The phase-3r live row proves
carrier 1 survives the bind, which is the property F1 destroyed — but
it tagged its fixture sink with `peerspeak.owned=true`, not the `1`
the contract pins and peerspeak actually emits. It would have passed
even if the real literal did not.

Adds PEERSPEAK_OWNED_VALUE so the fixture can name the producer's
value, and asserts it against the shared contract file alongside the
other two literals. The sink's name still deliberately avoids the
`peerspeak_owned_` prefix, so carrier 2 cannot stand in for carrier 1
in that row.

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

src/host/taint/mod.rs

@@ -136,6 +136,15 @@ pub const ECHO_CANCEL_GROUP_PREFIX: &str = "echo-cancel-";
 /// change that invalidates the phase 5 matrix.
 pub const PEERSPEAK_OWNED_PROP: &str = "peerspeak.owned";
 
+/// The value peerspeak emits for [`PEERSPEAK_OWNED_PROP`].
+///
+/// The consumer deliberately accepts **any** truthy value, not just this one
+/// (see the observer's `truthy`) — treating an unexpected value as "owned" is
+/// the fail-closed direction. This constant exists so live tests can tag a
+/// node with exactly what the producer sends, rather than something merely
+/// truthy that would pass even if the real literal did not.
+pub const PEERSPEAK_OWNED_VALUE: &str = "1";
+
 /// Ownership carrier 2: a `node.name` prefix (v3.5 §5.1, round 8).
 ///
 /// Matched as a **union** with [`PEERSPEAK_OWNED_PROP`] — either one makes a