feat(context): inject CLAUDE.md / AGENTS.md as L0 standing context

On session start, discover CLAUDE.md and AGENTS.md at the bound workspace root and inject
their (concatenated, header-labeled) contents as an L0 system context entry for every stage —
mirroring the .correx/project.toml ProjectProfile path end to end. Recorded as
AgentInstructionsBoundEvent (invariant #9) so replay reads the recorded fact, not the live
file; folded into SessionState.boundAgentInstructions and rendered by buildAgentInstructionsEntry
right after the project profile. AgentInstructionsLoader reads root-only, both files if present.
Bound via ServerModule.bindAgentInstructions alongside bindProjectProfile.

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

core/sessions/src/main/kotlin/com/correx/core/sessions/BoundAgentInstructions.kt

@@ -0,0 +1,7 @@
+package com.correx.core.sessions
+
+/** Snapshot of standing agent instructions (CLAUDE.md / AGENTS.md) bound at session start. */
+data class BoundAgentInstructions(
+    val sources: List<String>,
+    val content: String,
+)

core/sessions/src/main/kotlin/com/correx/core/sessions/DefaultSessionReducer.kt

@@ -1,5 +1,6 @@
 package com.correx.core.sessions
 
+import com.correx.core.events.events.AgentInstructionsBoundEvent
 import com.correx.core.events.events.OperatorProfileBoundEvent
 import com.correx.core.events.events.ProjectProfileBoundEvent
 import com.correx.core.events.events.SessionWorkspaceBoundEvent
@@ -61,6 +62,14 @@ class DefaultSessionReducer : SessionReducer {
             else -> state.boundProjectProfile
         }
 
+        val boundAgentInstructions = when (payload) {
+            is AgentInstructionsBoundEvent -> BoundAgentInstructions(
+                sources = payload.sources,
+                content = payload.content,
+            )
+            else -> state.boundAgentInstructions
+        }
+
         return state.copy(
             status = newStatus,
             createdAt = createdAt,
@@ -68,6 +77,7 @@ class DefaultSessionReducer : SessionReducer {
             boundWorkspace = boundWorkspace,
             boundProfile = boundProfile,
             boundProjectProfile = boundProjectProfile,
+            boundAgentInstructions = boundAgentInstructions,
         )
     }
 }

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionState.kt

@@ -10,4 +10,5 @@ data class SessionState(
     val boundWorkspace: BoundWorkspace? = null,
     val boundProfile: BoundProfile? = null,
     val boundProjectProfile: BoundProjectProfile? = null,
+    val boundAgentInstructions: BoundAgentInstructions? = null,
 )