Fix SonarQube "indexed twice" error for dispatcher-agent sources

[Copilot]

SonarQube Gradle plugin v6+ auto-detects source sets for every Kotlin JVM subproject. With :dispatcher-agent paths also explicitly listed in the root sonar {} block, the scanner encountered the same files via two paths, causing:

File dispatcher-agent/src/main/kotlin/.../DispatchDecisionApplier.kt
can't be indexed twice. Please check that inclusion/exclusion patterns
produce disjoint sets for main and test files

Changes

• build.gradle.kts (root): Remove dispatcher-agent/src/{main,test}/kotlin from sonar.sources/sonar.tests and remove dispatcher-agent binary paths from sonar.java.binaries/sonar.java.test.binaries. JUnit/JaCoCo aggregation paths stay in root. Added comment explaining the invariant.

• dispatcher-agent/build.gradle.kts: Add explicit sonar {} block that owns this module's source/test/binary configuration — the correct multi-module Gradle pattern where each subproject declares its own SonarQube settings:

  sonar {
      properties {
          property("sonar.sources", "src/main/kotlin")
          property("sonar.tests", "src/test/kotlin")
          property("sonar.java.binaries", "build/classes/kotlin/main")
          property("sonar.java.test.binaries", "build/classes/kotlin/test")
          property("sonar.sourceEncoding", "UTF-8")
      }
  }

• sonar-project.properties: Add dispatcher-agent paths to keep this file in sync (used for local CLI sonar-scanner runs, which have no Gradle subproject auto-detection).