docs/concepts/presence.md: replaced 8 curly quote and non-breaking
hyphen characters (U+201C/U+201D/U+2019/U+2011) with ASCII equivalents
so grep, copy-paste, and Mintlify search hit the right tokens.
Converted the 2-bullet Related list into a CardGroup adding cross-links
to gateway architecture and gateway protocol since presence is produced
by both surfaces.
docs/concepts/markdown-formatting.md: replaced 5 typography characters
(en-dash and curly quotes) with ASCII equivalents and converted the
2-bullet Related list into a CardGroup pointing at streaming/chunking
and system prompt.
docs/concepts/typing-indicators.md: replaced 4 typography characters
with ASCII equivalents and converted the 2-bullet Related list into a
CardGroup with the same Presence and Streaming cross-links.
Verified /concepts/streaming, /concepts/system-prompt,
/concepts/architecture, and /gateway/protocol targets all exist.
