Update trace-target references for the relocated rendezvous modules

Moving the nostr rendezvous engine to src/nostr/ (and mDNS to src/mdns/)
changed the module-path-derived tracing targets from
fips::discovery::nostr::* to fips::nostr::*. Update the RUST_LOG filters
in the NAT and mesh-lab test compose files and the resolve-peers-via-nostr
tutorial's debug recipe to the new targets so trace configs and the
documented journal-watch command keep emitting the intended lines.

Without this, the stun-faults suite's Phase-0 pre-flight (which greps the
daemon journal for the debug-level "STUN observation succeeded" /
"traversal: initiator STUN observed" lines) saw those lines suppressed —
the daemon behaved correctly, but the stale RUST_LOG target hid the
evidence. Test-harness and docs only; no source or behavior change.

docs/tutorials/resolve-peers-via-nostr.md

@@ -178,7 +178,7 @@ The resolution itself happens at debug-log level, so you will
 not see it in the default-level journal. The user-facing way to
 confirm everything worked is `fipsctl show peers` in the next
 step. (To watch the resolution in the journal, run the daemon
-manually with `RUST_LOG=fips::discovery::nostr=debug`; not
+manually with `RUST_LOG=fips::nostr=debug`; not
 necessary for this tutorial.)
 
 ## Step 5: Verify the resolved endpoint

testing/mesh-lab/compose-trace-nat.yml

@@ -2,7 +2,7 @@
 # relevant to NAT-traversal handshake-completion flake evidence
 # collection (ISSUE-2026-0027):
 #
-#   - fips::discovery::nostr            — overlay advert publish/consume
+#   - fips::nostr            — overlay advert publish/consume
 #                                          (where the cross-init race begins)
 #   - fips::transport::udp              — UDP socket bind/send/recv
 #                                          (where the punch packets flow)
@@ -33,7 +33,7 @@
 # is set and the suite is nat-lan.
 
 x-trace-rust-log: &trace-rust-log
-  RUST_LOG: "info,fips::discovery::nostr=trace,fips::transport::udp=trace,fips::node::lifecycle=trace,fips::node::handlers::handshake=trace,fips::node::handlers::forwarding=trace"
+  RUST_LOG: "info,fips::nostr=trace,fips::transport::udp=trace,fips::node::lifecycle=trace,fips::node::handlers::handshake=trace,fips::node::handlers::forwarding=trace"
 
 services:
   lan-a:

testing/nat/docker-compose.yml

@@ -27,7 +27,7 @@ x-fips-common: &fips-common
     - net.ipv6.conf.all.disable_ipv6=0
   restart: "no"
   environment:
-    - RUST_LOG=info,fips::discovery::nostr=debug,fips::node::lifecycle=debug
+    - RUST_LOG=info,fips::nostr=debug,fips::node::lifecycle=debug
 
 services:
   relay:
@@ -115,7 +115,7 @@ services:
     entrypoint:
       - /usr/local/bin/nat-node-entrypoint.sh
     environment:
-      - RUST_LOG=info,fips::discovery::nostr=debug,fips::node::lifecycle=debug
+      - RUST_LOG=info,fips::nostr=debug,fips::node::lifecycle=debug
       - DATA_IF=eth0
       - ROUTE_SUBNET=172.31.254.0/24
       - ROUTE_VIA=172.31.1.254
@@ -141,7 +141,7 @@ services:
     entrypoint:
       - /usr/local/bin/nat-node-entrypoint.sh
     environment:
-      - RUST_LOG=info,fips::discovery::nostr=debug,fips::node::lifecycle=debug
+      - RUST_LOG=info,fips::nostr=debug,fips::node::lifecycle=debug
       - DATA_IF=eth0
       - ROUTE_SUBNET=172.31.254.0/24
       - ROUTE_VIA=172.31.2.254
@@ -167,7 +167,7 @@ services:
     entrypoint:
       - /usr/local/bin/nat-node-entrypoint.sh
     environment:
-      - RUST_LOG=info,fips::discovery::nostr=debug,fips::node::lifecycle=debug
+      - RUST_LOG=info,fips::nostr=debug,fips::node::lifecycle=debug
       - DATA_IF=eth0
       - ROUTE_SUBNET=172.31.254.0/24
       - ROUTE_VIA=172.31.1.254
@@ -193,7 +193,7 @@ services:
     entrypoint:
       - /usr/local/bin/nat-node-entrypoint.sh
     environment:
-      - RUST_LOG=info,fips::discovery::nostr=debug,fips::node::lifecycle=debug
+      - RUST_LOG=info,fips::nostr=debug,fips::node::lifecycle=debug
       - DATA_IF=eth0
       - ROUTE_SUBNET=172.31.254.0/24
       - ROUTE_VIA=172.31.2.254