feat(k-ui): first slice: App trait + run loop, builders (column/row/text/button), flex layout, theme tokens (Whimsy Dark), tiny-skia + fontdue render (Noto Sans Latin subset), keyboard focus ring; tally demo; manifest memory key (pm spawns with it)

docs/apps.md

@@ -62,6 +62,8 @@ binary  = "snake"           # required: a file in the app's folder
 command = "snake"           # optional: what the shell runs it as (default: binary)
 author  = "K-OS"            # optional
 icon    = "icon.png"        # optional: a file in the app's folder
+memory  = "3 MiB"           # optional: how much it may use, KiB or MiB,
+                            # 64 KiB to 16 MiB (default 512 KiB)
 
 [capabilities]
 required = ["display"]      # cannot work without; denied = not installed