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/dm-channels.md

@@ -1,7 +1,7 @@
 # 1:1 Channel Design
 
 This page describes the design for first-class 1:1 (direct message) channels in
-quicproquo. Channels provide per-conversation authorisation, MLS-encrypted
+quicprochat. Channels provide per-conversation authorisation, MLS-encrypted
 payloads, message retention with TTL eviction, and backward compatibility with
 the legacy delivery model.