fix: eliminate all compiler warnings across client, relay, web

- Remove unused imports in featherchat.rs (tracing, QualityProfile)
- Remove unused comfort_noise field from CallEncoder (cn_level is used instead)
- Prefix unused _metrics_file in CliArgs
- Prefix unused _addr in Participant
- Remove unused RoomSlot struct and rooms field from web AppState
- Remove unused HashMap import from web main

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/wzp-client/src/call.rs

@@ -209,8 +209,6 @@ pub struct CallEncoder {
     timestamp_ms: u32,
     /// Silence detector for suppression.
     silence_detector: SilenceDetector,
-    /// Comfort noise generator for CN packets.
-    comfort_noise: ComfortNoise,
     /// Whether silence suppression is enabled.
     suppression_enabled: bool,
     /// Total frames suppressed (telemetry).
@@ -243,7 +241,6 @@ impl CallEncoder {
                 config.silence_threshold_rms,
                 config.silence_hangover_frames,
             ),
-            comfort_noise: ComfortNoise::new(config.comfort_noise_level),
             suppression_enabled: config.suppression_enabled,
             frames_suppressed: 0,
             cn_counter: 0,

crates/wzp-client/src/cli.rs

@@ -46,7 +46,7 @@ struct CliArgs {
     mnemonic: Option<String>,
     room: Option<String>,
     token: Option<String>,
-    metrics_file: Option<String>,
+    _metrics_file: Option<String>,
 }
 
 impl CliArgs {
@@ -220,7 +220,7 @@ fn parse_args() -> CliArgs {
         mnemonic,
         room,
         token,
-        metrics_file,
+        _metrics_file: metrics_file,
     }
 }
 

crates/wzp-client/src/featherchat.rs

@@ -11,10 +11,7 @@
 //! 5. Connects QUIC to relay for media
 
 use serde::{Deserialize, Serialize};
-use tracing::{error, info};
-
 use wzp_proto::packet::SignalMessage;
-use wzp_proto::QualityProfile;
 
 /// featherChat CallSignal types (mirrors warzone-protocol::message::CallSignalType).
 #[derive(Clone, Debug, Serialize, Deserialize)]