Phase 4: TollGate client detection + auto-payment

- New tollgate_client.c/h: detect upstream TollGate (kind=10021),
  auto-pay via nucula wallet, session monitoring with 20% renewal
- State machine: IDLE→DETECTING→NEEDS_PAY→PAYING→PAID→RENEWING
- Blocking: upstream payment before local services start
- Synchronous wallet init (was async task)
- Client config: enabled, steps_to_buy, renewal_threshold_pct
- Updated PLAN.md with Phases 4-7 (client, payout, bytes, CVM)
- Updated CHECKLIST.md with all new phase items
- 30 new unit tests (all passing), 116 total

1 files changed, 1 insertions, 0 deletions

diff --git a/main/CMakeLists.txt b/main/CMakeLists.txt
index df69283..be4d564 100644
--- a/main/CMakeLists.txt
+++ b/main/CMakeLists.txt
@@ -10,6 +10,7 @@ idf_component_register(SRCS "tollgate_main.c"
                             "nostr_event.c"
                             "geohash.c"
                             "wifistr.c"
+                            "tollgate_client.c"
                     INCLUDE_DIRS "."
                     REQUIRES esp_wifi esp_event esp_netif nvs_flash esp_http_server
                              lwip json esp_http_client mbedtls esp-tls log spiffs