docs: Formalize Synology NAS repo standards with REQUIREMENTS.md, maintenance instructions, and setup guides. Fix service typos and standardize filenames.

REQUIREMENTS.md

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+# Synology NAS Docker Service Requirements
+
+This document outlines the mandatory standards for services managed in this repository via Portainer.
+
+## 1. User Management
+- **Dedicated User**: Every service must have a dedicated local user created on the Synology DSM.
+- **Non-Root Execution**: Containers must run under the service-specific PUID and PGID whenever possible.
+- **Root Exception**: Only services that strictly require root privileges (e.g., Traefik, Cloudflared in some network modes) are allowed to run as root.
+
+## 2. File and Folder Structure
+- **Base Path**: `/volume1/docker/`
+- **Service Data**: All configuration, database, and system-related files must reside in `/volume1/docker/<service_name>`.
+- **User Data (Large)**: Large user-managed files (e.g., ebooks, movies, paperless documents) must reside in `/volume1/media/<type>/`.
+- **Hierarchy Example**:
+  - `/volume1/docker/calibre/` (Config, DB)
+  - `/volume1/media/ebooks/` (EPUB/PDF files)
+
+## 3. Deployment and Setup
+- **Idempotent Scripts**: Every service must include a `create_<service>_folders.sh` script.
+- **Setup Documentation**: Every service folder must contain a `SETUP.md` file documenting the end-to-end flow, highlighting manual pre-setup steps (user creation, ID lookup).
+- **Script Requirements**:
+  - Must use `mkdir -p` to handle existing directories.
+  - Must set correct ownership (`chown`) and permissions (`chmod`) based on the service user.
+  - Must be safe to run multiple times without causing errors or data loss.
+- **Stack Grouping**: It is encouraged to group related containers (e.g., App, DB, Redis) into a single Portainer stack file.
+
+## 4. Configuration
+- **Environment Variables**: Use `stack.env` or Portainer environment variables for sensitive data.
+- **Parametrization**: Ideally, use `${PUID}`, `${PGID}`, and `${TZ}` variables to maintain portability across different user accounts.