feat: replace bind-mount log pipeline with Docker log streaming

Services now print RFC 5424 to stdout; Docker captures via json-file driver.
A new host-side collector (decnet.web.collector) streams docker logs from all
running decky service containers and writes RFC 5424 + parsed JSON to the host
log file. The existing ingester continues to tail the .json file unchanged.
rsyslog can consume the .log file independently — no DECNET involvement needed.

Removes: bind-mount volume injection, _LOG_NETWORK bridge, log_target config
field and --log-target CLI flag, TCP syslog forwarding from service templates.

tests/test_log_file_mount.py

@@ -1,9 +1,6 @@
-"""Tests for log_file volume mount in compose generation."""
+"""Tests for compose generation — logging block and absence of volume mounts."""
 
-from pathlib import Path
-
-
-from decnet.composer import _CONTAINER_LOG_DIR, _resolve_log_file, generate_compose
+from decnet.composer import generate_compose, _DOCKER_LOGGING
 from decnet.config import DeckyConfig, DecnetConfig
 from decnet.distros import DISTROS
 
@@ -29,68 +26,48 @@ def _make_config(log_file: str | None = None) -> DecnetConfig:
     )
 
 
-class TestResolveLogFile:
-    def test_absolute_path(self, tmp_path):
-        log_path = str(tmp_path / "decnet.log")
-        host_dir, container_path = _resolve_log_file(log_path)
-        assert host_dir == str(tmp_path)
-        assert container_path == f"{_CONTAINER_LOG_DIR}/decnet.log"
+class TestComposeLogging:
+    def test_service_container_has_logging_block(self):
+        config = _make_config()
+        compose = generate_compose(config)
+        fragment = compose["services"]["decky-01-http"]
+        assert "logging" in fragment
+        assert fragment["logging"] == _DOCKER_LOGGING
 
-    def test_relative_path_resolves_to_absolute(self):
-        host_dir, container_path = _resolve_log_file("decnet.log")
-        assert Path(host_dir).is_absolute()
-        assert container_path == f"{_CONTAINER_LOG_DIR}/decnet.log"
+    def test_logging_driver_is_json_file(self):
+        config = _make_config()
+        compose = generate_compose(config)
+        fragment = compose["services"]["decky-01-http"]
+        assert fragment["logging"]["driver"] == "json-file"
 
-    def test_nested_filename_preserved(self, tmp_path):
-        log_path = str(tmp_path / "logs" / "honeypot.log")
-        _, container_path = _resolve_log_file(log_path)
-        assert container_path.endswith("honeypot.log")
+    def test_logging_has_rotation_options(self):
+        config = _make_config()
+        compose = generate_compose(config)
+        fragment = compose["services"]["decky-01-http"]
+        opts = fragment["logging"]["options"]
+        assert "max-size" in opts
+        assert "max-file" in opts
 
+    def test_base_container_has_no_logging_block(self):
+        """Base containers run sleep infinity and produce no app logs."""
+        config = _make_config()
+        compose = generate_compose(config)
+        base = compose["services"]["decky-01"]
+        assert "logging" not in base
 
-class TestComposeLogFileMount:
-    def test_no_log_file_no_volume(self):
-        config = _make_config(log_file=None)
+    def test_no_volume_mounts_on_service_container(self):
+        config = _make_config(log_file="/tmp/decnet.log")
+        compose = generate_compose(config)
+        fragment = compose["services"]["decky-01-http"]
+        assert not fragment.get("volumes")
+
+    def test_no_decnet_log_file_env_var(self):
+        config = _make_config(log_file="/tmp/decnet.log")
         compose = generate_compose(config)
         fragment = compose["services"]["decky-01-http"]
         assert "DECNET_LOG_FILE" not in fragment.get("environment", {})
-        volumes = fragment.get("volumes", [])
-        assert not any(_CONTAINER_LOG_DIR in v for v in volumes)
 
-    def test_log_file_sets_env_var(self, tmp_path):
-        config = _make_config(log_file=str(tmp_path / "decnet.log"))
+    def test_no_log_network_in_networks(self):
+        config = _make_config()
         compose = generate_compose(config)
-        fragment = compose["services"]["decky-01-http"]
-        env = fragment["environment"]
-        assert "DECNET_LOG_FILE" in env
-        assert env["DECNET_LOG_FILE"].startswith(_CONTAINER_LOG_DIR)
-        assert env["DECNET_LOG_FILE"].endswith("decnet.log")
-
-    def test_log_file_adds_volume_mount(self, tmp_path):
-        config = _make_config(log_file=str(tmp_path / "decnet.log"))
-        compose = generate_compose(config)
-        fragment = compose["services"]["decky-01-http"]
-        volumes = fragment.get("volumes", [])
-        assert any(_CONTAINER_LOG_DIR in v for v in volumes)
-
-    def test_volume_mount_format(self, tmp_path):
-        config = _make_config(log_file=str(tmp_path / "decnet.log"))
-        compose = generate_compose(config)
-        fragment = compose["services"]["decky-01-http"]
-        mount = next(v for v in fragment["volumes"] if _CONTAINER_LOG_DIR in v)
-        host_part, container_part = mount.split(":")
-        assert Path(host_part).is_absolute()
-        assert container_part == _CONTAINER_LOG_DIR
-
-    def test_host_log_dir_created(self, tmp_path):
-        log_dir = tmp_path / "newdir"
-        config = _make_config(log_file=str(log_dir / "decnet.log"))
-        generate_compose(config)
-        assert log_dir.exists()
-
-    def test_volume_not_duplicated(self, tmp_path):
-        """Same mount must not appear twice even if fragment already has volumes."""
-        config = _make_config(log_file=str(tmp_path / "decnet.log"))
-        compose = generate_compose(config)
-        fragment = compose["services"]["decky-01-http"]
-        log_mounts = [v for v in fragment["volumes"] if _CONTAINER_LOG_DIR in v]
-        assert len(log_mounts) == 1
+        assert "decnet_logs" not in compose["networks"]