refactor(toolintent): one SessionContext read-model for the gates

Replace the single-purpose sessionReadPaths plumbing with a SessionContext
{reads, writes, activeTask} folded by SessionContextProjection over the session
stream — the read-model every anti-hallucination gate consumes (plane-2 rules via
ToolCallAssessmentInput.session; tool gates via a port, next).

- reads: completions whose recorded capability includes FILE_READ.
- writes: the resolved paths the orchestrator already records on each completion's
  receipt.affectedEntities (FileAffectingTool) — no param-parsing reinvention.
- activeTask: null for now; populated once claim records a session fact.

ReadBeforeWriteRule now reads input.session.reads; ReadFilesProjection is retired.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestrator.kt

@@ -69,7 +69,7 @@ import com.correx.core.events.events.ToolReceipt
 import com.correx.core.events.events.ToolRequest
 import com.correx.core.events.risk.RiskAction
 import com.correx.core.events.risk.RiskSummary
-import com.correx.core.toolintent.ReadFilesProjection
+import com.correx.core.toolintent.SessionContextProjection
 import com.correx.core.toolintent.ToolCallAssessmentInput
 import com.correx.core.toolintent.ToolCallAssessor
 import com.correx.core.toolintent.WorkspacePolicy
@@ -970,7 +970,7 @@ abstract class SessionOrchestrator(
                 paramRoles = tool?.paramRoles ?: emptyMap(),
                 writeManifest = writeManifest,
                 sessionEgressHosts = sessionEgressHosts,
-                sessionReadPaths = resolveSessionReadPaths(sessionId),
+                session = resolveSessionContext(sessionId),
             ),
         )
         emit(
@@ -1001,15 +1001,14 @@ abstract class SessionOrchestrator(
     }
 
     /**
-     * Folds this session's file_read tool events through [ReadFilesProjection] into the set of paths
-     * it has successfully read — the input to [com.correx.core.toolintent.rules.ReadBeforeWriteRule].
-     * Replay-safe (reads the log, never live state); empty before any read completes.
+     * Folds this session's tool events through [SessionContextProjection] into the read-model the
+     * anti-hallucination gates consume (reads, writes, active task). Replay-safe (reads the log,
+     * never live state); empty before anything has happened.
      */
-    internal fun resolveSessionReadPaths(sessionId: SessionId): Set<String> {
-        val projection = ReadFilesProjection(sessionId)
+    internal fun resolveSessionContext(sessionId: SessionId): com.correx.core.toolintent.SessionContext {
+        val projection = SessionContextProjection(sessionId)
         return eventStore.read(sessionId)
             .fold(projection.initial()) { acc, event -> projection.apply(acc, event) }
-            .readPaths
     }
 
     private suspend fun buildSchemaEntries(