relay: address the account by phone number and pass the message via -m

signal-cli 0.14.7 parses an all-digit -a value as a phone number (the
numeric account name never resolves), and the message is a -m option,
not a positional (a positional is parsed as a second recipient).
Verified live: corrected invocation returns type SUCCESS.

scripts/signal-relay.py

@@ -33,8 +33,12 @@ from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 # podman bridge subnet (10.89.0.0/16) only, keeping the unauthenticated
 # endpoint off the rest of the LAN.
 LISTEN_ADDR = ("192.168.0.143", 18093)
-SIGNAL_CLI = "/usr/local/bin/signal-cli"
-SIGNAL_ACCOUNT = "318311"
+# The account is addressed by phone number: signal-cli 0.14.7's -a flag
+# parses an all-digit value as a phone number and never falls back to the
+# accounts.json name (the numeric name 318311 dies with "Invalid account
+# (phone number)"). The number is a number, not a credential — the
+# credential is the account state under ~/.local/share/signal-cli.
+SIGNAL_ACCOUNT = "+12062476336"
 SIGNAL_TO = "+12062476336"
 
 # The relay is a safety net, not the rate limiter: Alertmanager already
@@ -86,7 +90,8 @@ def send_signal(text):
         return False
     try:
         proc = subprocess.run(
-            [SIGNAL_CLI, "-a", SIGNAL_ACCOUNT, "-o", "json", "send", SIGNAL_TO, text],
+            [SIGNAL_CLI, "-a", SIGNAL_ACCOUNT, "-o", "json", "send", SIGNAL_TO,
+             "-m", text],
             capture_output=True, text=True, timeout=30,
         )
     except subprocess.TimeoutExpired: