M-INTEROCEPTION P5: dream-recall builtin engram_dreams_json (honesty rail)

Adds a read-only builtin that returns the curiosity_scan InternalStateEvents
created after a `since` cutoff that are STILL RESIDENT — "what I was chewing on
while you were gone." curiosity_scan is identified by the marker the soul writes
into each ISE's JSON content; heartbeat and other ISEs are excluded.

HARD honesty rail: it reports only ISEs still in the buffer. Anything rotated
out by the 48h engram_prune_telemetry is simply ABSENT — rotated-out = "I don't
remember", never a synthesized/plausible dream. Purely additive, no flag.

The HTTP route (GET /api/dreams?since=) is DEFERRED to cutover per the elc-drift
blocker (regenerating engram/dist diverges with no source change); the builtin
is exercised directly by the pure-C gate.

MEASURED on a copy: seeded 3 curiosity_scan (ancient/1h/now) + 1 heartbeat;
before prune dreams returned exactly the 3 curiosity_scan (heartbeat excluded);
after the 48h prune the ancient one was ABSENT (not confabulated), leaving 2;
the since-filter returned only the post-cutoff event; no returned id was ever
fabricated. ASan+UBSan clean.

engram/test/run_interoception_p5.sh

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+# M-INTEROCEPTION P5 gate: dream-recall builtin engram_dreams_json (honesty rail).
+set -u
+HERE="$(cd "$(dirname "$0")" && pwd)"
+RT="$HERE/../../lang/runtime/el_runtime.c"
+ST="$HERE/../../lang/runtime/engram_store.c"
+GEO="$HERE/../../lang/runtime/engram_geometry.c"
+VIDX="$HERE/../../lang/runtime/engram_vindex.c"
+INC="$HERE/../../lang/runtime"
+WORK="$(mktemp -d /tmp/engram-p5-XXXXXX)"
+export HOME="$WORK/home"; mkdir -p "$HOME"
+unset ENGRAM_STORE
+fail=0
+
+echo "== compile =="
+gcc -O1 -std=c11 -I "$INC" "$HERE/test_interoception_p5_dreams.c" "$RT" "$ST" "$GEO" "$VIDX" \
+    -lcurl -lm -o "$WORK/p5" 2>"$WORK/cc.log" || { echo "COMPILE FAILED"; cat "$WORK/cc.log"; rm -rf "$WORK"; exit 1; }
+
+D="$WORK/d"; mkdir -p "$D"
+"$WORK/p5" "$D" > "$WORK/out.txt" 2>&1 || { echo "FAIL run"; cat "$WORK/out.txt"; fail=1; }
+cat "$WORK/out.txt" | sed 's/^/    /'
+
+echo
+echo "== assertions =="
+python3 - "$WORK/out.txt" <<'PY'
+import sys,re,json
+L={}
+for line in open(sys.argv[1]):
+    line=line.strip()
+    m=re.match(r'(BEFORE|AFTER) (\[.*\])',line)
+    if m: L[m.group(1)]=json.loads(m.group(2)); continue
+    m=re.match(r'PRUNED (\d+)',line)
+    if m: L['PRUNED']=int(m.group(1)); continue
+    m=re.match(r'SINCE (\d+) (\[.*\])',line)
+    if m: L['SINCE']=json.loads(m.group(2))
+rc=0
+def check(c,msg):
+    global rc; print(("  PASS: " if c else "  FAIL: ")+msg)
+    if not c: rc=1
+before_ids={d["id"] for d in L["BEFORE"]}
+after_ids={d["id"] for d in L["AFTER"]}
+since_ids={d["id"] for d in L["SINCE"]}
+check(before_ids=={"cur_old","cur_mid","cur_recent"}, f"before prune: all 3 curiosity_scan, heartbeat excluded (got {sorted(before_ids)})")
+check("hb_recent" not in before_ids, "heartbeat ISE never appears (not a dream)")
+check(L["PRUNED"]==1, f"prune rotated out exactly the ancient ISE (pruned={L['PRUNED']})")
+check(after_ids=={"cur_mid","cur_recent"}, f"after prune: rotated-out cur_old is ABSENT, not confabulated (got {sorted(after_ids)})")
+check("cur_old" not in after_ids, "honesty rail: pruned dream is gone = 'I don't remember', never synthesized")
+check(since_ids=={"cur_recent"}, f"since filter returns only events after the cutoff (got {sorted(since_ids)})")
+# no fabrication: every returned id was one we seeded
+seeded={"cur_old","cur_mid","cur_recent","hb_recent"}
+allret=before_ids|after_ids|since_ids
+check(allret<=seeded, f"no fabricated entries — every returned id was seeded ({sorted(allret)})")
+sys.exit(rc)
+PY
+[ $? -ne 0 ] && fail=1
+
+echo
+echo "== ASan+UBSan =="
+gcc -O1 -g -std=c11 -fsanitize=address,undefined -fno-sanitize-recover=undefined \
+    -I "$INC" "$HERE/test_interoception_p5_dreams.c" "$RT" "$ST" "$GEO" "$VIDX" \
+    -lcurl -lm -o "$WORK/p5.san" 2>"$WORK/san_cc.log" || { echo "SAN COMPILE FAILED"; tail -25 "$WORK/san_cc.log"; fail=1; }
+if [ -x "$WORK/p5.san" ]; then
+  export ASAN_OPTIONS=detect_leaks=0
+  DS="$WORK/ds"; mkdir -p "$DS"
+  "$WORK/p5.san" "$DS" >/dev/null 2>"$WORK/san.log"
+  if grep -qiE 'runtime error|AddressSanitizer|Sanitizer|ERROR: ' "$WORK/san.log"; then
+    echo "  FAIL: sanitizer findings:"; grep -iE 'runtime error|Sanitizer|ERROR' "$WORK/san.log" | head; fail=1
+  else echo "  ok: ASan+UBSan clean"; fi
+fi
+
+echo
+if [ "$fail" -eq 0 ]; then echo "====== P5 DREAM-RECALL GATE: PASS ======"; else echo "====== P5 DREAM-RECALL GATE: FAIL ======"; fi
+rm -rf "$WORK"
+exit $fail