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/roadmap/authz-plan.md

@@ -1,7 +1,7 @@
 # Auth, Devices, and Tokens
 
 This page describes the authentication, device management, and authorisation
-design for quicproquo. It introduces account and device identities, gates
+design for quicprochat. It introduces account and device identities, gates
 server operations by authenticated identity, enforces rate and size limits, and
 binds MLS identity keys to accounts.