fix(launcher): localize image-missing placeholder + drop dead icons.lua

- markdown.lua: M.render now accepts an optional `t` 6th arg (ctx.t).
  When present, the image-missing fallback string is looked up via the
  new `image_missing_fmt` key in strings.lua. Callers without t (the
  launcher-test bytecopy) get the hardcoded English string verbatim,
  matching previous behavior.
- panels/detail.lua: both md.render call sites now thread ctx.t through.
- strings.lua: add image_missing_fmt = "[image missing: %s]".
- icons.lua: deleted. The v0.2.0 status-glyph helper was replaced by
  dep_glyph_* string keys in v0.3.0; grep confirmed no remaining refs.
- manifest.module: bump 0.3.2 -> 0.3.3.

panels/detail.lua

@@ -50,7 +50,7 @@ function M.render(ctx)
     if ctx.selected_entry == "news" then
         ensure_md(ctx.launcher_dir)
         local body = ctx.news_body_blocks or {}
-        md.render(body, p.x + PADDING, p.y + PADDING, p.w - 2 * PADDING, nil)
+        md.render(body, p.x + PADDING, p.y + PADDING, p.w - 2 * PADDING, nil, ctx.t)
         return
     end
 
@@ -84,7 +84,7 @@ function M.render(ctx)
     -- Description (rendered MD).
     ensure_md(ctx.launcher_dir)
     cur_y = md.render(mc.blocks, p.x + PADDING, cur_y,
-                      p.w - 2 * PADDING, entry.id)
+                      p.w - 2 * PADDING, entry.id, ctx.t)
 
     cur_y = cur_y + 12