v0.0.45: call ring tones + group calls

Direct call ringing:
- Incoming: oscillator ring tone (440/480Hz, on/off pattern)
- Outgoing: ringback tone (2s on, 4s off) while waiting for answer
- Browser Notification API for background incoming calls
- All tones stop on answer/reject/hangup
- Notification permission requested on first click

Group calls:
- /gcall — start a group call (notifies all group members)
- /gjoin — join an active group call
- /gleave-call — leave group call
- /gmute — toggle per-group call notification mute (localStorage)
- Participant tracking (joined/left messages with count)
- Group call signal via group message broadcast (JSON type: group_call)
- Call bar shows "Join Call" button when group call is active
- Audio via same WZP bridge (room = gc-<groupname>)

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

warzone/Cargo.lock

@@ -2956,7 +2956,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-client"
-version = "0.0.44"
+version = "0.0.45"
 dependencies = [
  "anyhow",
  "argon2",
@@ -2989,7 +2989,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-mule"
-version = "0.0.44"
+version = "0.0.45"
 dependencies = [
  "anyhow",
  "clap",
@@ -2998,7 +2998,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-protocol"
-version = "0.0.44"
+version = "0.0.45"
 dependencies = [
  "base64",
  "bincode",
@@ -3023,7 +3023,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-server"
-version = "0.0.44"
+version = "0.0.45"
 dependencies = [
  "anyhow",
  "axum",
@@ -3054,7 +3054,7 @@ dependencies = [
 
 [[package]]
 name = "warzone-wasm"
-version = "0.0.44"
+version = "0.0.45"
 dependencies = [
  "base64",
  "bincode",