Canary Testbench test pages

• LNK-01: Section, thumbnail, separator, text and two link buttons.
• LNK-02: The LNK-01 payload served from a separate JSON URL instead of inline.
• LNK-03: Exactly 3,000 bytes renders; 3,001 bytes should not.
• LNK-04: Any key outside the allowed list should invalidate the whole payload.
• LNK-05: The cap is 10 gallery items across the whole embed.
• LNK-06: variant=nested puts a Container in a Container; variant=text makes the top level a Text Display.
• LNK-07: Can a website make text that looks like real mentions?
• LNK-08: Blurred until clicked; the video should show a frame and never autoplay.
• LNK-09: delay=9000 should still render; delay=11000 passes the 10-second fetch limit.
• LNK-10: Same as LNK-01, posted by the bot, a webhook and your alt, then replied to and forwarded.