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/el-compiler/src/codegen-js.el

@@ -1202,7 +1202,7 @@ fn codegen_js_inner(stmts: [Map<String, Any>], source: String, bundle_mode: Bool
         js_emit_line(js_strip_es_exports(runtime_content))
         js_emit_line("")
     } else {
-        js_emit_line("// Runtime: foundation/el/el-compiler/runtime/el_runtime.js")
+        js_emit_line("// Runtime: foundation/el/runtime/el_runtime.js")
         js_emit_line("import \"./el_runtime.js\";")
     }
     // In module mode: destructure all builtins off globalThis.__el so call