fix elb linker: remove runtime imports from el-install, add --clean, catch in dev/stage CI

el-install.el explicitly imported runtime/*.el modules (string, env, fs, exec,
json, http), which elb compiled to .c files in the shared dist/bin out_dir.
Linking those alongside el_runtime.c caused multiple definition errors for
every runtime function (http_get, http_patch, etc.). The runtime .el files are
thin wrappers over seed primitives already compiled into el_runtime.c — no
import needed.

Fixes:
- Remove all explicit runtime imports from el-install.el (root cause)
- Add --clean to every elb invocation in sdk-release.yaml so each build
  starts with a clean out_dir (defense-in-depth against stale .c files)
- Add elb build + epm/el-install build steps to ci-dev.yaml and ci-stage.yaml
  so linker errors are caught on every PR, not just stage->main

.gitea/workflows/sdk-release.yaml

@@ -77,7 +77,7 @@ jobs:
           ABS_ELC="$(pwd)/dist/platform/elc"
           ABS_RUNTIME="$(pwd)/el-compiler/runtime"
           ABS_OUT="$(pwd)/dist/bin"
-          (cd ../epm && "$ABS_ELB" --elc="$ABS_ELC" --runtime="$ABS_RUNTIME" --out="$ABS_OUT")
+          (cd ../epm && "$ABS_ELB" --clean --elc="$ABS_ELC" --runtime="$ABS_RUNTIME" --out="$ABS_OUT")
           chmod +x dist/bin/epm
           echo "epm built"
 
@@ -88,7 +88,7 @@ jobs:
           ABS_ELC="$(pwd)/dist/platform/elc"
           ABS_RUNTIME="$(pwd)/el-compiler/runtime"
           ABS_OUT="$(pwd)/dist/bin"
-          (cd tools/install && "$ABS_ELB" --elc="$ABS_ELC" --runtime="$ABS_RUNTIME" --out="$ABS_OUT")
+          (cd tools/install && "$ABS_ELB" --clean --elc="$ABS_ELC" --runtime="$ABS_RUNTIME" --out="$ABS_OUT")
           chmod +x dist/bin/el-install
           echo "el-install built"