Root cause: When 3+ projects generated pending simultaneously, Bot's
pending_approval_scanner made 20-40 Discord API calls in one tick
(sequential await), triggering Discord 429 rate limits which blocked
the entire scanner for 10-30s, freezing ALL signal delivery.
Two fixes:
1. _get_channel(): Replace guild.fetch_channels() (API call) with
discord.utils.get(guild.channels) (in-memory cache). Eliminates
redundant API calls + Lock contention when multiple projects arrive.
2. pending_approval_scanner: Per-tick caps (5 new + 5 status) prevent
one tick from monopolizing Discord API quota. Excess items are
naturally processed in subsequent 3-second ticks.
37c0aae41c