Replace custom logging with tracing crate and RUST_LOG env var

- Remove custom logging module and init_logging function
- Update main.rs to use tracing_subscriber with EnvFilter
- Remove log_level from global config structure
- Update documentation and tests to use RUST_LOG
- Format long lines in config.rs and test files for better readability

dist/INSTALL.md

@@ -104,7 +104,6 @@ Edit `/etc/pollux/config.toml`:
 bind_host = "0.0.0.0"
 port = 1965
 max_concurrent_requests = 1000
-log_level = "info"
 
 # Host configuration
 ["example.com"]
@@ -113,6 +112,22 @@ cert = "/etc/pollux/tls/cert.pem"
 key = "/etc/pollux/tls/key.pem"
 ```
 
+### Logging Configuration
+
+Pollux uses structured logging with the `tracing` crate. Configure log levels using the `RUST_LOG` environment variable:
+
+```bash
+# Set log level before starting the service
+export RUST_LOG=info
+sudo systemctl start pollux
+
+# Or for debugging
+export RUST_LOG=pollux=debug
+sudo systemctl restart pollux
+
+# Available levels: error, warn, info, debug, trace
+```
+
 ### Content Setup
 
 ```bash
@@ -194,7 +209,8 @@ See `config.toml` for all available options. Key settings:
 - `bind_host`: IP/interface to bind to (global)
 - `port`: Listen port (1965 is standard, per host override possible)
 - `max_concurrent_requests`: Connection limit (global)
-- `log_level`: Logging verbosity (global, per host override possible)
+
+Logging is configured via the `RUST_LOG` environment variable (see Logging Configuration section).
 
 ## Certificate Management