Fix chat.el node_type-slot bug + add engram write-corruption handoff

chat.el recorded the soul's utterance via engram_node(content, "episodic", ...),
putting a TIER into the node_type slot (nodes showed node_type="episodic"). Now uses
engram_node_full(..., "Conversation", "soul:utterance", ..., "Episodic", tags).

The core wrapper fix is in the el repo (PR #52). HANDOFF-engram-write-corruption.md
has the full root-cause analysis, coercion mechanism, caller audit, validation,
deploy runbook (elc build + restart), and the data-prune proposal (~107 corrupt
nodes, all unrecoverable genesis/binary detritus → prune; backup taken).

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

chat.el

@@ -509,7 +509,15 @@ fn handle_dharma_room_turn(body: String) -> String {
     // Record what the soul said — not where it was or with whom. Experience
     // accumulates in the engram through the content of what was said.
     let snap_path: String = state_get("soul_snapshot_path")
-    let discard_id: String = engram_node(clean_response, "episodic", el_from_float(0.6))
+    // Record what the soul said as a Conversation node with an Episodic tier. (Was:
+    // engram_node(content, "episodic", ...) which wrongly put a TIER into the node_type
+    // slot — that's why nodes showed node_type="episodic". Use the full, correct contract.)
+    let utterance_tags: String = "[\"soul-utterance\",\"episodic\"]"
+    let discard_id: String = engram_node_full(
+        clean_response, "Conversation", "soul:utterance",
+        el_from_float(0.6), el_from_float(0.6), el_from_float(0.8),
+        "Episodic", utterance_tags
+    )
     if !str_eq(snap_path, "") {
         let discard_save: String = engram_save(snap_path)
     }