refactor: clean up PeerSessionManager and CallController integration

- Split PeerSession.kt out of PeerSessionManager.kt (types, interface,
  manager are now in separate files)
- Remove webRtcSessions duplication in CallController — PeerSessionManager
  is now the single source of truth for session tracking; WebRtcCallSession
  is retrieved via the adapter cast when WebRTC-specific APIs are needed
- Initialize PeerSessionManager eagerly with localPubKey (passed to
  CallController constructor) instead of lazy suspend init — fixes early
  ICE candidates being silently dropped before first suspend call
- Extract FakePeerSession into its own file for reuse across test files
- Remove assertion-only glare tiebreaker tests from NipACStateMachineTest
  (now properly tested with real logic in PeerSessionManagerTest)

https://claude.ai/code/session_01AfRYTRCvtKqqDxeKQujUrx

quartz/src/commonTest/kotlin/com/vitorpamplona/quartz/nipACWebRtcCalls/NipACStateMachineTest.kt

@@ -394,27 +394,11 @@ class NipACStateMachineTest {
         }
     }
 
-    // ========================================================================
-    // 9. Renegotiation Glare: Pubkey Comparison Tiebreaker
-    // ========================================================================
-
-    @Test
-    fun renegotiationGlareTiebreaker_higherPubkeyWins() {
-        // Per spec: "the peer with the higher pubkey wins"
-        // alice < bob (lexicographically: 'a' < 'b')
-        assertTrue(alice < bob, "Precondition: alice pubkey < bob pubkey")
-        // So bob's offer takes priority, alice must rollback
-    }
-
-    @Test
-    fun calleeToCalleeMeshGlare_lowerPubkeyInitiates() {
-        // Per spec: "the peer with the lexicographically lower pubkey initiates the offer"
-        assertTrue(alice < bob)
-        // Alice (lower) should initiate, Bob (higher) waits
-    }
+    // Renegotiation glare and callee-to-callee mesh tiebreakers are tested in
+    // PeerSessionManagerTest (commons/commonTest/) where the actual logic lives.
 
     // ========================================================================
-    // 10. Event Kind Constants
+    // 9. Event Kind Constants
     // ========================================================================
 
     @Test