chore: rename quicproquo → quicprochat in docs, Docker, CI, and packaging

Rename all project references from quicproquo/qpq to quicprochat/qpc
across documentation, Docker configuration, CI workflows, packaging
scripts, operational configs, and build tooling.

- Docker: crate paths, binary names, user/group, data dirs, env vars
- CI: workflow crate references, binary names, artifact names
- Docs: all markdown files under docs/, SDK READMEs, book.toml
- Packaging: OpenWrt Makefile, init script, UCI config (file renames)
- Scripts: justfile, dev-shell, screenshot, cross-compile, ai_team
- Operations: Prometheus config, alert rules, Grafana dashboard
- Config: .env.example (QPQ_* → QPC_*), CODEOWNERS paths
- Top-level: README, CONTRIBUTING, ROADMAP, CLAUDE.md

sdks/go/proto/node/node.capnp

@@ -1,10 +1,10 @@
-# node.capnp — Go-annotated copy of the quicproquo node schema.
+# node.capnp — Go-annotated copy of the quicprochat node schema.
 # This adds Go package annotations needed by capnpc-go.
 @0xd5ca5648a9cc1c28;
 
 using Go = import "/go.capnp";
 $Go.package("node");
-$Go.import("quicproquo.dev/sdk/go/proto/node");
+$Go.import("quicprochat.dev/sdk/go/proto/node");
 
 interface NodeService {
   uploadKeyPackage @0 (identityKey :Data, package :Data, auth :Auth) -> (fingerprint :Data);