Replace accumulate-by-concatenation loops with native_list_append + str_join.
Eliminates quadratic memory growth when processing large source files.
This is the v2 compiler state — what produced /tmp/elc-v2.
- .gitea/workflows/sdk-release.yaml: build elc from bootstrap, run tests,
publish latest release, dispatch el-sdk-updated to downstream repos
- install.sh: one-command El SDK install from Gitea release