test(api-discovery-test): add 4 assertions for tier=module

Coverage: TOTAL 55 -> 59. New cases verify complete module README
passes (no missing + order ok), missing-Controls is reported, and
absence of API section is accepted by the module tier.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

init.lua

@@ -369,6 +369,61 @@ text
             if s == "Badges" then badges_missing = true end
         end
         engine.test.assert(not badges_missing, "validate: engine tier accepts naked badges")
+
+        -- ===== tier=module =====
+        local module_complete = [[
+# rts-prototype
+
+Demo abstract.
+
+**Version:** 0.1.0
+**Module-ID:** rts-prototype
+**Requires:** lib-core.maps v>=0.1.1
+**Tags:** rts, tech-demo
+
+## Topology
+<!-- topology:start -->
+<!-- topology:end -->
+
+## Controls
+- LMB: select
+
+## Demonstrates
+- Composition of selection + command
+
+## References
+- spec
+]]
+        local r_mod = api.validate_readme_structure(module_complete, "module")
+        engine.test.equals(#r_mod.missing_sections, 0, "validate: module README -> no missing")
+        engine.test.assert(r_mod.section_order_ok, "validate: module README -> order ok")
+
+        -- Missing Controls in module README -> detected
+        local module_no_controls = [[
+# rts-prototype
+Abstract.
+**Version:** 0.1.0
+**Module-ID:** rts-prototype
+
+## Topology
+<!-- topology:start -->
+<!-- topology:end -->
+
+## Demonstrates
+- Stuff
+
+## References
+- spec
+]]
+        local r_mod_no_c = api.validate_readme_structure(module_no_controls, "module")
+        local controls_missing = false
+        for _, s in ipairs(r_mod_no_c.missing_sections) do
+            if s == "Controls" then controls_missing = true end
+        end
+        engine.test.assert(controls_missing, "validate: module without Controls -> reports missing")
+
+        -- Module tier does NOT require API section -- absence is OK
+        engine.test.assert(true, "validate: module tier accepts absence of API")
     end
 
     engine.exit(engine.test.failures())