Establish config loading and logging infrastructure

First working milestone of the Rust rewrite. Implements the two
foundational systems every other component depends on:

- TOML-based layered config (beds.toml + env.toml override) replacing
  the PHP XML config system, fully deserialized into typed structs via
  serde — no runtime string key lookups, shape enforced at compile time
- Structured logging via tracing + tracing-journald, with optional
  console mirror, initialized from config before any services start

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

config/beds.toml

@@ -0,0 +1,33 @@
+debug = false
+syslog = true
+syslog_mirror_console = true
+audit_on = false
+journal_on = false
+
+[id]
+env_name = "production"
+version = "1.0"
+wbid = "ga"
+
+[broker_services]
+queue_tag = "prod_"
+vhost = "prod"
+timer_violation = 3000
+records_per_xfer = 5000
+keepalive = true
+heartbeat = 60
+use_ssl = false
+cert_path = "/etc/rabbitmq"
+
+[broker_services.app_server]
+host = "localhost"
+port = 5672
+api_port = 15672
+user = "beds"
+pass = "changeme"
+rpi = 50
+
+[broker_services.app_server.instances]
+r_broker = 2
+w_broker = 2
+m_broker = 0