feat(sim): slim-mode submodule minimization

Three changes:
- vendor/logos-lez-rln bump: drops unused top-level logos-delivery
  submodule (~1.3 GB saved per fresh clone).
- setup_and_run.sh: gate lssa + logos-execution-zone-module init on
  SIM_NETWORK=local (or SIM_FULL_SUBMODS=1). Default Docker setup now
  pulls only logos-delivery-module (+ nested logos-delivery), saving
  ~11 GB of lssa for slim/testnet fresh clones.
- run_simulation.sh: stop requiring lssa/ to exist when discovering
  LEZ_RLN_DIR in the sibling-checkout layout.
- README: slim-mode minimum-submodule recipe + rationale.

simulations/mix_lez_chat/README.md

@@ -119,6 +119,27 @@ What stays shared vs. fresh:
 
 **Security:** the supply signing key being in the repo is acceptable only because testnet does not charge gas and the tokens are test tokens with no real value.
 
+### Slim mode (`SIM_SLIM=1`, testnet only)
+
+`SIM_SLIM=1 SIM_NETWORK=testnet ./run_simulation.sh --fresh` skips `run_setup` entirely and reuses the shipped `config_account` + cached `payment_account` from `vendor/logos-lez-rln/testnet/`. Two consequences:
+
+- No `lez-rln/run_setup` binary build is required. Combined with the submodule split below, a fresh clone can run the sim without ever invoking `cargo` from `lez-rln/`.
+- All slim-mode runs share one on-chain payment account — concurrent runs across devs will race on its nonce. Use serially.
+
+**Minimum submodule set for slim mode:**
+
+```bash
+git clone --branch feat/logos-delivery <repo> logos-chat
+cd logos-chat
+git submodule update --init vendor/logos-lez-rln vendor/nwaku vendor/nimbus-build-system vendor/nim-protobuf-serialization vendor/npeg vendor/blake2 vendor/libchat vendor/nim-ffi
+(cd vendor/logos-lez-rln && git submodule update --init logos-delivery-module)
+(cd vendor/logos-lez-rln/logos-delivery-module && git submodule update --init --recursive vendor/logos-delivery)
+```
+
+The previously-required `lssa` (~11 GB) and `logos-execution-zone-module` clones are unnecessary for slim mode — both are fetched via nix flake from GitHub when building the wallet/RLN modules. The top-level `vendor/logos-lez-rln/logos-delivery` submodule was removed entirely (the active copy is the nested `logos-delivery-module/vendor/logos-delivery`).
+
+For the local-sequencer flow (`SIM_NETWORK=local`) or to hack on the wallet/sequencer source, init the extras: `(cd vendor/logos-lez-rln && git submodule update --init lssa logos-execution-zone-module)`. The Docker bootstrap (`setup_and_run.sh`) gates these on `SIM_NETWORK=local` automatically; pass `SIM_FULL_SUBMODS=1` to force the wide init.
+
 ## `--fresh` behavior
 
 When `--fresh` is passed:

simulations/mix_lez_chat/run_simulation.sh

@@ -22,7 +22,7 @@ if [ -z "$LEZ_RLN_DIR" ] && [ -d "$LOGOS_CHAT_DIR/vendor/logos-lez-rln/lez-rln"
 fi
 for candidate in "$LOGOS_CHAT_DIR/.." "$LOGOS_CHAT_DIR/../logos-lez-rln"; do
     [ -n "$LEZ_RLN_DIR" ] && break
-    [ -d "$candidate/lez-rln" ] && [ -d "$candidate/lssa" ] && LEZ_RLN_DIR="$(cd "$candidate" && pwd)" && break
+    [ -d "$candidate/lez-rln" ] && LEZ_RLN_DIR="$(cd "$candidate" && pwd)" && break
 done
 [ -z "$LEZ_RLN_DIR" ] && { echo "FATAL: Cannot find logos-lez-rln repo. Set LEZ_RLN_DIR or run: git submodule update --init --recursive"; exit 1; }
 

simulations/mix_lez_chat/setup_and_run.sh

@@ -63,10 +63,19 @@ elif [ -f "/tmp/guest-bins/rln_registration.bin" ]; then
     log "Using guest binaries from /tmp/guest-bins/"
 fi
 log "Initializing nested submodules in vendor/logos-lez-rln..."
+# Slim default: only logos-delivery-module (+ its nested logos-delivery) is
+# required to build the chat/delivery/mix Nim modules. lssa and
+# logos-execution-zone-module are fetched via flake.nix from GitHub when nix
+# builds the wallet/rln modules, so the local clones aren't needed unless the
+# dev is running a local sequencer (SIM_NETWORK=local) or hacking those repos.
+SUBMODS=(logos-delivery-module)
+if [ "${SIM_NETWORK:-testnet}" = "local" ] || [ "${SIM_FULL_SUBMODS:-0}" = "1" ]; then
+    SUBMODS+=(lssa logos-execution-zone-module)
+fi
 (cd vendor/logos-lez-rln && \
-    git submodule update --init lssa logos-delivery logos-delivery-module logos-execution-zone-module && \
+    git submodule update --init "${SUBMODS[@]}" && \
     git checkout -- . && \
-    for d in lssa logos-delivery logos-delivery-module logos-execution-zone-module; do \
+    for d in "${SUBMODS[@]}"; do \
         (cd "$d" && git checkout -- .); \
     done && \
     cd logos-delivery-module && git submodule update --init vendor/logos-delivery)

vendor/logos-lez-rln

@@ -1 +1 @@
-Subproject commit 61d366173cd095f9491f9fd49c3c452b14f930d8
+Subproject commit 430998ec9e19cabe2f0dd50915566bc6ddffaa41