chore(prompt): tell telegram models to prefer bullets over tables

Telegram has no native table syntax. The gateway auto-rewrites pipe
tables into row-group bullets (see previous commit), but letting models
know up front means they emit the clean form directly instead of
relying on post-processing to synthesize headings.

Also helps users whose MEMORY.md formatting policies were being
overridden — the platform hint now carries the guidance.

agent/prompt_builder.py

@@ -310,6 +310,10 @@ PLATFORM_HINTS = {
         "Standard markdown is automatically converted to Telegram format. "
         "Supported: **bold**, *italic*, ~~strikethrough~~, ||spoiler||, "
         "`inline code`, ```code blocks```, [links](url), and ## headers. "
+        "Telegram has NO table syntax — prefer bullet lists or labeled "
+        "key: value pairs over pipe tables (any tables you do emit are "
+        "auto-rewritten into row-group bullets, which you can produce "
+        "directly for cleaner output). "
         "You can send media files natively: to deliver a file to the user, "
         "include MEDIA:/absolute/path/to/file in your response. Images "
         "(.png, .jpg, .webp) appear as photos, audio (.ogg) sends as voice "