sync(launcher-test): markdown.lua picks up image_missing localization

markdown.lua now mirrors the launcher byte-for-byte: M.render takes an
optional t 6th arg that the launcher threads its ctx.t through for the
image-missing placeholder. Pure-additive parameter — existing test
callers (which never invoke M.render) are unaffected.

manifest.lib: bump 0.2.0 -> 0.3.0. The render-signature change is
API-shaped; downstream consumers that call the helper directly may want
to opt in to the new arg.

markdown.lua

@@ -176,7 +176,11 @@ local function render_spans(spans, x, y, max_w, size)
     return cur_y + line_h
 end
 
-function M.render(blocks, x, y, max_w, module_id_for_imgs)
+-- `t` (optional, 6th arg) is the launcher's ctx.t string-lookup function.
+-- When present, M.render uses it to localize the image-missing placeholder
+-- via the `image_missing_fmt` key. Callers that don't have a t (e.g. tests)
+-- may pass nil; the hardcoded English fallback then renders verbatim.
+function M.render(blocks, x, y, max_w, module_id_for_imgs, t)
     local cur_y = y
     for _, b in ipairs(blocks) do
         if b.type == "h1" then
@@ -216,7 +220,9 @@ function M.render(blocks, x, y, max_w, module_id_for_imgs)
                     -- assume a 16:9 max_w-wide image for layout.
                     cur_y = cur_y + math.floor(max_w * 9 / 16) + PARA_GAP
                 else
-                    engine.render.draw_text("[image missing: " .. b.src .. "]",
+                    local missing_text = t and t("image_missing_fmt", b.src)
+                                            or ("[image missing: " .. b.src .. "]")
+                    engine.render.draw_text(missing_text,
                                             x, cur_y, BODY_SIZE, COLOR_DIM)
                     local _, h = engine.render.measure_text("[image]", BODY_SIZE)
                     cur_y = cur_y + h + PARA_GAP