feat(launcher-test): cover frontmatter + markdown parsers

Extends run_tests from 12 -> ~46 asserts: 10 frontmatter cases (simple
field, no-frontmatter passthrough, numeric field, multi-line body,
non-string input, empty meta) and ~25 markdown cases (headers,
bullets, ordered, images, bold/italic/code spans, paragraph joining,
mixed mid-block). frontmatter.lua and markdown.lua are byte-identical
copies of the launcher's helpers; smoke.sh enforces no drift via
git hash-object.

manifest.lib

@@ -1,7 +1,7 @@
 {
     "id": "lib-management.launcher-test",
     "role": "test",
-    "version": "0.1.0",
+    "version": "0.2.0",
     "api_min": "0.1",
     "deps": []
 }