collect: add --dry flag to run push server without WeConnect

When --dry is set, WeConnect login and data collection are skipped.
The push server still starts and serves preloaded 24 h history to
connecting clients — useful for GUI testing without a live vehicle.
Credentials are not required in dry-run mode.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

collect.py

@@ -71,15 +71,20 @@ def run(args: argparse.Namespace) -> None:
         log.error("Unknown domain(s): %s.  Available: %s", unknown, list(ALL_DOMAINS))
         sys.exit(1)
 
+    if args.dry:
+        log.info("Dry-run mode — skipping WeConnect login")
+        wc = None
+        vehicle = None
+        vin = args.vin or "UNKNOWN"
+    else:
         log.info("Connecting to WeConnect…")
         wc = we_connect.connect(args.username, args.password)
-
         vehicle, err = we_connect.select_vehicle(wc, args.vin)
         if err:
             log.error(err)
             sys.exit(1)
-
         vin = vehicle.vin.value
+
     log.info("Vehicle: %s", vin)
 
     logs_dir = Path(args.log_dir)
@@ -94,6 +99,10 @@ def run(args: argparse.Namespace) -> None:
     current_day = datetime.now(timezone.utc).date()
     store = load_store(out, vin, args.interval)
     push_store_ref["current"] = store
+
+    if args.dry:
+        log.info("Push server running on %s:%d — no live collection  (Ctrl-C to stop)", args.host, args.port)
+    else:
         log.info(
             "Collecting [%s] every %ds → %s  (Ctrl-C to stop)",
             ", ".join(domains),
@@ -103,6 +112,7 @@ def run(args: argparse.Namespace) -> None:
 
     try:
         while True:
+            if not args.dry:
                 today = datetime.now(timezone.utc).date()
                 if today != current_day:
                     out = auto_out_path(logs_dir, vin)
@@ -174,6 +184,11 @@ def main() -> None:
         help="Keep only the last N records per file (default: unlimited)",
     )
     p.add_argument("-v", "--verbose", action="store_true", help="Enable debug logging")
+    p.add_argument(
+        "--dry",
+        action="store_true",
+        help="Skip WeConnect login and data collection; run push server only (for GUI testing)",
+    )
     p.add_argument(
         "--list-domains",
         action="store_true",
@@ -217,7 +232,7 @@ def main() -> None:
     args.port     = int(creds_data.get("port", 9999))
     args.log_dir  = creds_data.get("log_dir", "./logs")
 
-    if not args.username or not args.password:
+    if not args.dry and (not args.username or not args.password):
         p.error(
             "Username and password are required.  "
             "Provide them in the credentials file or via -u/-p / WC_USER / WC_PASS."