chore: remove Docker support entirely from this fork

Never used by this fork's own distribution (install.sh/x-ui.sh is the
only supported install path), AmneziaWG structurally can't run in the
Alpine-based image anyway, and Docker Hub publishing was failing on
every release for lack of configured credentials. Removed Dockerfile,
docker-compose.yml, DockerEntrypoint.sh, DockerInit.sh, .dockerignore,
and the docker.yml CI workflow; dropped the now-dead "Docker" README
subsection (all 7 languages), the "Docker image"/"Docker Compose"
options from the issue/PR templates, and corrected claude-bot.yml's
now-stale references to the deleted files, the never-actually-ours
ghcr.io/mhsanaei/3x-ui image, and (caught in passing) an already-stale
claim that Windows is a supported platform.

Left untouched: generic container-runtime adaptations that apply
regardless of image source (x-ui.sh's running-in-docker detection,
the virtual-interface-name filters, the DNS-over-container-network
note) and deploy/test/smoke-noninteractive.sh, which uses Docker only
as its own test sandbox, not as something this repo ships.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/architecture.md

@@ -274,11 +274,10 @@ node heartbeat every 5s, periodic traffic resets (hourly/daily/weekly/monthly).
 ├── docs/                     # Markdown docs (this file, custom-subscription-templates.md, …)
 ├── media/                    # README images
 │
-├── Dockerfile / docker-compose.yml / DockerEntrypoint.sh / DockerInit.sh   # Container build/run
 ├── install.sh / update.sh / x-ui.sh                        # VPS install + management CLI
 ├── x-ui.service.*  / x-ui.rc                               # systemd units (debian/rhel/arch) + rc script
 ├── windows_files/                                          # Windows service support
-└── .github/workflows/        # CI: ci.yml, codeql.yml, docker.yml, release.yml, smoke.yml,
+└── .github/workflows/        # CI: ci.yml, codeql.yml, release.yml, smoke.yml,
                               #     mutation.yml, cleanup_caches.yml, claude-bot.yml
 ```
 
@@ -556,11 +555,9 @@ npm run build        # gen:api + vite build → outputs to internal/web/dist (th
 **Full local loop:** `cd frontend && npm run build` (refresh embedded `dist/`) → back to repo
 root → `go build ./...` / `go run main.go`.
 
-**Docker:** `docker compose up -d` (uses `Dockerfile` + `DockerEntrypoint.sh`).
-
 **CI** (`.github/workflows/`): `ci.yml` (build/test/lint), `codeql.yml` (security scan),
-`smoke.yml` (smoke tests), `mutation.yml` (mutation testing), `docker.yml` + `release.yml`
-(multi-arch image + release builds), `cleanup_caches.yml`, `claude-bot.yml` (issue bot).
+`smoke.yml` (smoke tests), `mutation.yml` (mutation testing), `release.yml`
+(multi-arch release builds), `cleanup_caches.yml`, `claude-bot.yml` (issue bot).
 
 ---