engram: WAL persistence + integrity hardening + single canonical runtime

Establish lang/runtime/ as the ONE canonical el runtime (from the active
runtime that carries hebb/emb persistence + the new WAL); repoint the el CI
publish, engram build, elb default, and in-repo build scripts to it; delete
the el-compiler/runtime + lang/releases/ forks; add scripts/check-single-runtime.sh
drift guard.

Fixes a live prod bug: the el CI published el-runtime-c/-h from the LAGGING
el-compiler fork (0 hebb refs), so the shipped soul never persisted Hebbian
edge weights — learned co-activation was wiped on every restart. Publishing
from canonical ships the stranded 'learning that cannot outlive the process'
fix.

WAL storage engine + integrity fixes (DELETE->tombstone + store-layer
protection, safe data-dir default) ride in behind ENGRAM_WAL (default off =
byte-identical to today). Verified: engram elb per-module build clean, WAL
gate 66/66, native smoke ok, drift-guard green.

ui/examples/native-hello-android/build.sh

@@ -18,7 +18,7 @@ set -euo pipefail
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 EL_LANG_ROOT="${SCRIPT_DIR}/../../../lang"
 EL_UI_ROOT="${SCRIPT_DIR}/../.."
-EL_RUNTIME="${EL_LANG_ROOT}/el-compiler/runtime"
+EL_RUNTIME="${EL_LANG_ROOT}/runtime"
 EL_NATIVE_VESSEL="${EL_UI_ROOT}/vessels/el-native/src/main.el"
 EL_APP_ENTRY="${EL_UI_ROOT}/examples/native-hello/src/main.el"
 EL_MANIFEST="${EL_UI_ROOT}/examples/native-hello/manifest.el"