Remove the capnp compiler requirement from prerequisites (protobuf-src
vendors protoc automatically). Update building.md for 9 crates and the
justfile commands. Rewrite running-the-server.md with accurate v2 flags
(--allow-insecure-auth, --sealed-sender, --plugin-dir, --ws-listen,
--webtransport-listen, --federation-enabled, QPQ_PRODUCTION). Update
docker.md to remove capnproto install from builder stage description.
Delete bot-sdk.md and generators.md (removed crates). Update testing.md
with the accurate 301-test breakdown across 9 crates and the AUTH_LOCK
note for E2E tests. Update coding-standards.md dependency table to list
prost as primary serialisation, capnp as legacy-only, and add opaque-ke.
Christian Nennemann
f7a7f672b4