The typing-indicator refresh loop in BasePlatformAdapter._keep_typing
awaited each send_typing call unconditionally. Each call is an HTTP
round-trip to the platform API (Telegram/Discord), normally ~100ms. When
the same network instability that causes upstream provider timeouts
(e.g. Anthropic capacity blips slowing first-token latency past the
120s stream-read timeout) also slows the platform typing API to
multi-second response times, the refresh loop stalls inside the await.
Platform-side typing expires at ~5s, so the bubble dies and stays dead
until the stuck send_typing call returns — right when the user most
needs the 'still working' signal and instead sees a bot that looks
dead, then asks 'wtf are you doing' which itself interrupts the
eventually-recovering turn.
Bound each send_typing with asyncio.wait_for (1.5s cap, derived from
interval so it's always below the 2s cadence). Slow calls get abandoned
so the next scheduled tick fires a fresh send_typing on schedule. As
long as any one of them reaches the platform within its ~5s
typing-expiry window, the bubble stays visible across the stall.
Also catches non-timeout send_typing exceptions (transient HTTP errors)
so one bad tick doesn't terminate the whole loop.
Tests: 4 new in tests/gateway/test_keep_typing_timeout.py covering
slow-send non-blocking, fast-send still-awaited, exception resilience,
and paused-chat regression guard.
