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.

lang/tools/install.sh

@@ -44,7 +44,7 @@ INCLUDE_DIR="${PREFIX}/include"
 LIB_DIR="${PREFIX}/lib"
 
 ELC_SRC="${EL_ROOT}/dist/platform/elc"
-RUNTIME_SRC="${EL_ROOT}/el-compiler/runtime"
+RUNTIME_SRC="${EL_ROOT}/runtime"
 STDLIB_SRC="${EL_ROOT}/runtime"
 
 echo "==> Installing El framework to ${PREFIX}"

lang/tools/new-project.sh

@@ -42,7 +42,7 @@ fi
 # Discover el_runtime.c
 EL_RUNTIME=""
 SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-LOCAL_RUNTIME="${SCRIPT_DIR}/../el-compiler/runtime/el_runtime.c"
+LOCAL_RUNTIME="${SCRIPT_DIR}/../runtime/el_runtime.c"
 if [[ -f "${LOCAL_RUNTIME}" ]]; then
     EL_RUNTIME="$(cd "$(dirname "${LOCAL_RUNTIME}")" && pwd)/$(basename "${LOCAL_RUNTIME}")"
     EL_INCLUDE="$(dirname "${EL_RUNTIME}")"