feat(transitions): tasks_ready predicate for execution loop

New TasksReady condition driven by EvaluationContext.readyTaskCount,
fed at resolve time via a kernel-declared ReadyTaskCounter interface
implemented in apps/server over TaskService (keeps core:kernel
decoupled from core:tasks). Loops a graph while ready>0, exits at 0.

core/transitions/src/main/kotlin/com/correx/core/transitions/conditions/TasksReady.kt

@@ -0,0 +1,9 @@
+package com.correx.core.transitions.conditions
+
+import com.correx.core.transitions.evaluation.EvaluationContext
+import com.correx.core.transitions.graph.TransitionCondition
+
+/** True while the session's project still has tasks ready to claim — the execution loop's gate. */
+object TasksReady : TransitionCondition {
+    override fun evaluate(context: EvaluationContext) = context.readyTaskCount > 0
+}

core/transitions/src/main/kotlin/com/correx/core/transitions/evaluation/EvaluationContext.kt

@@ -11,4 +11,5 @@ data class EvaluationContext(
     val artifacts: Map<ArtifactId, ArtifactState> = emptyMap(),
     val variables: Map<String, String> = emptyMap(),
     val artifactContent: Map<ArtifactId, String> = emptyMap(),
+    val readyTaskCount: Int = 0,
 )

core/transitions/src/test/kotlin/com/correx/core/transitions/conditions/TransitionConditionTest.kt

@@ -30,6 +30,18 @@ class TransitionConditionTest {
         assertTrue(AlwaysTrue.evaluate(baseContext))
     }
 
+    // TasksReady
+
+    @Test
+    fun `TasksReady true when ready count positive`() {
+        assertTrue(TasksReady.evaluate(baseContext.copy(readyTaskCount = 1)))
+    }
+
+    @Test
+    fun `TasksReady false when no ready tasks`() {
+        assertFalse(TasksReady.evaluate(baseContext))
+    }
+
     // ArtifactPresent
 
     @Test