refactor: strip DECNET tokens from container-visible surface

Rename the container-side logging module decnet_logging → syslog_bridge
(canonical at templates/syslog_bridge.py, synced into each template by
the deployer). Drop the stale per-template copies; setuptools find was
picking them up anyway. Swap useradd/USER/chown "decnet" for "logrelay"
so no obvious token appears in the rendered container image.

Apply the same cloaking pattern to the telnet template that SSH got:
syslog pipe moves to /run/systemd/journal/syslog-relay and the relay
is cat'd via exec -a "systemd-journal-fwd". rsyslog.d conf rename
99-decnet.conf → 50-journal-forward.conf. SSH capture script:
/var/decnet/captured → /var/lib/systemd/coredump (real systemd path),
logger tag decnet-capture → systemd-journal. Compose volume updated
to match the new in-container quarantine path.

SD element ID shifts decnet@55555 → relay@55555; synced across
collector, parser, sniffer, prober, formatter, tests, and docs so the
host-side pipeline still matches what containers emit.

templates/mysql/Dockerfile

@@ -5,13 +5,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     python3 \
     && rm -rf /var/lib/apt/lists/*
 
-COPY decnet_logging.py /opt/decnet_logging.py
+COPY syslog_bridge.py /opt/syslog_bridge.py
 COPY server.py /opt/server.py
 COPY entrypoint.sh /entrypoint.sh
 RUN chmod +x /entrypoint.sh
 
 EXPOSE 3306
-RUN useradd -r -s /bin/false -d /opt decnet \
+RUN useradd -r -s /bin/false -d /opt logrelay \
  && apt-get update && apt-get install -y --no-install-recommends libcap2-bin \
  && rm -rf /var/lib/apt/lists/* \
  && (find /usr/bin/ -maxdepth 1 -name 'python3*' -type f -exec setcap 'cap_net_bind_service+eip' {} \; 2>/dev/null || true)
@@ -19,5 +19,5 @@ RUN useradd -r -s /bin/false -d /opt decnet \
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
   CMD kill -0 1 || exit 1
 
-USER decnet
+USER logrelay
 ENTRYPOINT ["/entrypoint.sh"]

templates/mysql/decnet_logging.py

@@ -1,89 +0,0 @@
-#!/usr/bin/env python3
-"""
-Shared RFC 5424 syslog helper for DECNET service templates.
-
-Services call syslog_line() to format an RFC 5424 message, then
-write_syslog_file() to emit it to stdout — Docker captures it, and the
-host-side collector streams it into the log file.
-
-RFC 5424 structure:
-  <PRI>1 TIMESTAMP HOSTNAME APP-NAME PROCID MSGID [SD-ELEMENT] MSG
-
-Facility: local0 (16), PEN for SD element ID: decnet@55555
-"""
-
-from datetime import datetime, timezone
-from typing import Any
-
-# ─── Constants ────────────────────────────────────────────────────────────────
-
-_FACILITY_LOCAL0 = 16
-_SD_ID = "decnet@55555"
-_NILVALUE = "-"
-
-SEVERITY_EMERG   = 0
-SEVERITY_ALERT   = 1
-SEVERITY_CRIT    = 2
-SEVERITY_ERROR   = 3
-SEVERITY_WARNING = 4
-SEVERITY_NOTICE  = 5
-SEVERITY_INFO    = 6
-SEVERITY_DEBUG   = 7
-
-_MAX_HOSTNAME = 255
-_MAX_APPNAME  = 48
-_MAX_MSGID    = 32
-
-# ─── Formatter ────────────────────────────────────────────────────────────────
-
-def _sd_escape(value: str) -> str:
-    """Escape SD-PARAM-VALUE per RFC 5424 §6.3.3."""
-    return value.replace("\\", "\\\\").replace('"', '\\"').replace("]", "\\]")
-
-
-def _sd_element(fields: dict[str, Any]) -> str:
-    if not fields:
-        return _NILVALUE
-    params = " ".join(f'{k}="{_sd_escape(str(v))}"' for k, v in fields.items())
-    return f"[{_SD_ID} {params}]"
-
-
-def syslog_line(
-    service: str,
-    hostname: str,
-    event_type: str,
-    severity: int = SEVERITY_INFO,
-    timestamp: datetime | None = None,
-    msg: str | None = None,
-    **fields: Any,
-) -> str:
-    """
-    Return a single RFC 5424-compliant syslog line (no trailing newline).
-
-    Args:
-        service:    APP-NAME (e.g. "http", "mysql")
-        hostname:   HOSTNAME (decky node name)
-        event_type: MSGID    (e.g. "request", "login_attempt")
-        severity:   Syslog severity integer (default: INFO=6)
-        timestamp:  UTC datetime; defaults to now
-        msg:        Optional free-text MSG
-        **fields:   Encoded as structured data params
-    """
-    pri     = f"<{_FACILITY_LOCAL0 * 8 + severity}>"
-    ts      = (timestamp or datetime.now(timezone.utc)).isoformat()
-    host    = (hostname or _NILVALUE)[:_MAX_HOSTNAME]
-    appname = (service  or _NILVALUE)[:_MAX_APPNAME]
-    msgid   = (event_type or _NILVALUE)[:_MAX_MSGID]
-    sd      = _sd_element(fields)
-    message = f" {msg}" if msg else ""
-    return f"{pri}1 {ts} {host} {appname} {_NILVALUE} {msgid} {sd}{message}"
-
-
-def write_syslog_file(line: str) -> None:
-    """Emit a syslog line to stdout for Docker log capture."""
-    print(line, flush=True)
-
-
-def forward_syslog(line: str, log_target: str) -> None:
-    """No-op stub. TCP forwarding is now handled by rsyslog, not by service containers."""
-    pass

templates/mysql/server.py

@@ -9,7 +9,7 @@ attempts as JSON.
 import asyncio
 import os
 import struct
-from decnet_logging import syslog_line, write_syslog_file, forward_syslog
+from syslog_bridge import syslog_line, write_syslog_file, forward_syslog
 
 NODE_NAME     = os.environ.get("NODE_NAME", "dbserver")
 SERVICE_NAME   = "mysql"