Docker: Build Optimization and Enhanced Non-Root/Volumeless Support (#5024)

* docker: optimize build layers and enhance permission handling

- Pre-created hardcoded dirs in Dockerfile to support volumeless non-root runs.
- Enhanced slightly docker-entrypoint.sh with robust volume detection and safer chown logic.
- Included legacy 'backups' directory... again.
- Added dos2unix to install list.
- Updated .dockerignore
- Updated comments
- Smaller fixes

* fix(docker): removed unnecessary comment, and the... *sighs* backups dir, again

* Exclude DS_Store everywhere

* Exclude tests and all jsconfigs from docker images

* Exclude local plugins from docker builds

* fix(docker): backups are back... yay xD

* feat(docker): add robust healthcheck script

- Added `docker/healthcheck.cjs`: A standalone, dependency-free Node.js script for verifying server status.
- Updated `Dockerfile`: Added HEALTHCHECK instruction and script copy step.
- Features: Auto-detects port from env/config, handles IPv4/IPv6 fallback, auto-retries HTTPS on socket hangup, and sets custom User-Agent.

* Fix .dockerignore permission

* Revert "feat(docker): add robust healthcheck script"

This reverts commit fa634fb08884cdef9245a12271cb9a13b487365f.

---------

Co-authored-by: Cohee <18619528+Cohee1207@users.noreply.github.com>

.dockerignore

@@ -1,21 +1,61 @@
+# --- Git & CI ---
 .git
 .github
-.vscode
-node_modules
-npm-debug.log
-readme*
-Start.bat
-/dist
-/backups
-cloudflared.exe
-access.log
-/data
-/cache
-.DS_Store
-/public/scripts/extensions/third-party
-/colab
-.gemini
+.gitignore
+
+# --- Docker ---
+/Dockerfile
+/.dockerignore
+/docker/docker-compose.yml
 /docker/config
 /docker/extensions
 /docker/data
 /docker/plugins
+/public/scripts/extensions/third-party
+
+# --- Plugins (keep only package files) ---
+/plugins/*
+!/plugins/package.json
+!/plugins/package-lock.json
+
+# --- The Folders ---
+/backups
+/cache
+/colab
+/data
+/dist
+/node_modules
+/tests
+
+# --- Sensitive Info ---
+**/.env*
+**/*.pem
+**/certs
+
+# --- Documentation ---
+readme*
+*.md
+Update-Instructions.txt
+
+# --- OS & System Junk ---
+**/.DS_Store
+*.bat
+*.cmd
+*.exe
+start.sh
+
+# --- Dev Config ---
+.editorconfig
+.eslintrc.cjs
+.eslintrc*
+.vscode
+**/jsconfig.json
+.npmignore
+.gemini
+replit.nix
+.replit
+.nomedia
+
+# -- Logs & Temp ---
+*.log
+**/tmp