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

docs/src/architecture/data-flow.md

@@ -1,13 +1,13 @@
 # End-to-End Data Flow
 
-This page traces the three core data flows through the quicproquo system:
+This page traces the three core data flows through the quicprochat system:
 registration, group creation, and message exchange. Each flow is illustrated
 with an ASCII sequence diagram showing control-plane (AS) and data-plane (DS)
 traffic.
 
 Throughout these flows the server is **MLS-unaware** -- it stores and forwards
 opaque byte blobs without parsing their MLS content. All RPC calls use the v2
-Protobuf framing protocol over QUIC (ALPN: `qpq`, port 5001).
+Protobuf framing protocol over QUIC (ALPN: `qpc`, port 5001).
 
 ---