feat(camera-test): migrate to test-lib (manifest.lib + run_tests) (Test-Opt Phase 3.3)

Per ADR-0037 Tests-as-Libs Convention. Renamed on Gitea + moved
locally. History preserved.

init.lua

@@ -5,7 +5,9 @@
 local camera = require("lib-core.camera")
 local T      = engine.test
 
-function init(ctx)
+local M = {}
+
+function M.run_tests(ctx)
     -- State setters/getters (3)
     camera.set_target(100, 200)
     local t = camera.target()
@@ -62,3 +64,5 @@ function init(ctx)
     -- Hygiene: reset bounds for any subsequent loads (init-only-lifecycle but defensive)
     camera.clear_bounds()
 end
+
+return M