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/BOOTSTRAP.md

@@ -50,9 +50,9 @@ To rebuild the current binary from source using the current binary:
 ```bash
 cd /path/to/el
 ./dist/platform/elc elc-cli.el elc-new.c
-cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
+cc -std=c11 -I runtime -lcurl -lpthread \
    -o dist/platform/elc-new \
-   elc-new.c el-compiler/runtime/el_runtime.c
+   elc-new.c runtime/el_runtime.c
 ```
 
 Verify self-hosting by using `elc-new` to recompile itself and diffing the outputs.
@@ -288,14 +288,14 @@ The codegen tracks declared names per C scope. When `count` is already in `decla
 
 ## 3. The Runtime API
 
-All runtime functions are declared in `el-compiler/runtime/el_runtime.h`. Every compiled El program links against `el-compiler/runtime/el_runtime.c`.
+All runtime functions are declared in `runtime/el_runtime.h`. Every compiled El program links against `runtime/el_runtime.c`.
 
 All values are `el_val_t` (`int64_t`). Strings are pointers cast through `int64_t` using `EL_STR(s)` / `EL_CSTR(v)` macros.
 
 Canonical compile command:
 ```bash
-cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
-   -o <out> <prog>.c el-compiler/runtime/el_runtime.c
+cc -std=c11 -I runtime -lcurl -lpthread \
+   -o <out> <prog>.c runtime/el_runtime.c
 ```
 
 ### I/O
@@ -794,8 +794,8 @@ Using your minimal implementation, compile `elc-cli.el` (which imports the entir
 python3 minimal_elc.py elc-cli.el > elc-new.c
 
 # Build with the runtime
-cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
-   -o elc-new elc-new.c el-compiler/runtime/el_runtime.c
+cc -std=c11 -I runtime -lcurl -lpthread \
+   -o elc-new elc-new.c runtime/el_runtime.c
 ```
 
 ### Step 5: Verify Self-Hosting
@@ -803,8 +803,8 @@ cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
 ```bash
 # Compile elc-cli.el with the new compiler
 ./elc-new elc-cli.el elc-v2.c
-cc -std=c11 -I el-compiler/runtime -lcurl -lpthread \
-   -o elc-v2 elc-v2.c el-compiler/runtime/el_runtime.c
+cc -std=c11 -I runtime -lcurl -lpthread \
+   -o elc-v2 elc-v2.c runtime/el_runtime.c
 
 # Compile again with the second-generation compiler
 ./elc-v2 elc-cli.el elc-v3.c
@@ -880,9 +880,9 @@ This is the planned path. It does not exist yet.
 | `el-compiler/src/parser.el` | Recursive descent parser. `parse(tokens)` → AST. All statement and expression forms | 1071 |
 | `el-compiler/src/codegen.el` | C code emitter. `codegen(stmts, source)` → (streams to stdout). Expression codegen, statement codegen, function codegen, type tracking, capability enforcement, temporal type dispatch | 2721 |
 | `el-compiler/src/codegen-js.el` | JavaScript backend. `codegen_js(stmts, source)` → JS source | ~500 |
-| `el-compiler/runtime/el_runtime.h` | Full runtime API declaration | 755 |
-| `el-compiler/runtime/el_runtime.c` | Full runtime implementation | large |
-| `el-compiler/runtime/el_runtime.js` | JS runtime | — |
+| `runtime/el_runtime.h` | Full runtime API declaration | 755 |
+| `runtime/el_runtime.c` | Full runtime implementation | large |
+| `runtime/el_runtime.js` | JS runtime | — |
 | `elb.el` | Build coordinator. Reads `manifest.el`, walks import graph, compiles modules, links binary. The `.NET`-style incremental build model | 367 |
 | `elc-combined.el` | Pre-merged single-file bootstrap edition (for early bootstrap iterations) | large |
 | `spec/language.md` | Language specification v1.2.0 | — |