Initial release: self-hostable APT repository server and CLI

urapt is a self-hostable APT repository server with a companion CLI for
pushing and managing Debian .deb packages.

Server (urapt-server):
- REST API + APT endpoint, SQLite storage (pure-Go modernc driver, no CGO)
- .deb files stored content-addressed on disk, reference-counted for dedup
- Server-managed RSA-4096 OpenPGP signing key (ProtonMail/go-crypto)
- APT indices (Release/InRelease/Packages[.gz/.xz]) generated on demand
  from the DB, cached in memory, signed with the server key
- Full APT model: repositories -> distributions -> components -> architectures
- Bearer-token auth for REST; HTTP Basic auth for private-repo APT reads
- First registrant becomes admin; repo-scoped permissions
  (read/write/read-write/admin) plus owner and server-admin roles
- Multipart package push with control-field extraction, list/show/delete,
  pool serving, blob ref-count cleanup
- Audit log

CLI (urapt):
- register/login/logout/whoami, token management
- repo/distro/component/arch CRUD, member management
- push/pull/ls/show/rm for packages
- apt-config helper that emits apt setup commands (key, sources.list,
  auth.conf for private repos)

Packaging & docs:
- Dockerfile (multi-stage distroless), docker-compose.yml, sample config
- README quick start, architecture overview, config reference, security notes
- PLAN.md design blueprint, CHANGELOG.md, GPL-3.0 LICENSE
- GitHub Actions CI (test, lint, cross-build for linux/darwin amd64/arm64)
- Makefile release target producing static binaries + tarballs + checksums

Tests cover the data-access layer, auth/permission checks, APT index
generation, .deb parsing, GPG signing, the REST API, and the typed API
client. Verified end-to-end on a Raspberry Pi (arm64) pushing and installing
a real package.

docker-compose.yml

@@ -0,0 +1,18 @@
+services:
+  urapt-server:
+    build: .
+    image: urapt-server:latest
+    ports:
+      - "8080:8080"
+    volumes:
+      - urapt-data:/data
+    environment:
+      URAPT_BIND: "0.0.0.0:8080"
+      URAPT_BASE_URL: "http://localhost:8080"
+      URAPT_STORE_DIR: "/data/store"
+      # URAPT_OPEN_REGISTRATION: "true"
+      # URAPT_SIGNING_KEY_USER_ID: "urapt-server <apt.example.com>"
+    restart: unless-stopped
+
+volumes:
+  urapt-data: