Keep wave huddles pending for placeholder profiles

[klopez4212]

Summary

• Keep wave huddle actions disabled while DM participant profile data is placeholder data from a previous users-batch query
• Add a users-batch delay knob to the e2e bridge
• Add smoke coverage for profile-only bot wave huddles waiting through the placeholder window
• Split ChannelPaneProps into a type-only sibling file so ChannelPane.tsx stays under the desktop file-size guard

Tests

• ./bin/pnpm --dir desktop exec biome check --write src/features/channels/ui/ChannelPane.tsx src/features/channels/ui/ChannelPane.types.ts src/features/channels/ui/ChannelScreen.tsx src/testing/e2eBridge.ts tests/helpers/bridge.ts tests/e2e/mentions.spec.ts
• ./bin/pnpm --dir desktop typecheck
• ./bin/pnpm --dir desktop check:file-sizes
• git diff --check
• ./bin/pnpm --dir desktop build
• ./bin/pnpm --dir desktop exec playwright test tests/e2e/mentions.spec.ts -g "wave attachment huddle waits for placeholder profile-only bot data|wave attachment huddle waits for delayed bot DM pubkey|system agent avatar huddle passes profile-only bot pubkey|system agent profile huddle passes profile-only bot pubkey" --project=smoke