Consolidate user-configurable files into data directory

[markoceri]

Summary

This PR reorganizes the project structure by moving all user-modifiable files and directories into a single root-level folder named data.

The following items have been relocated:

• Collection of user optimization policies : optimization_policies/ $\rightarrow$ data/policies/
• Collection of rule examples : example_rules/ $\rightarrow$ data/examples/rules/
• Application database file : edgemining.db $\rightarrow$ data/db/edgemining.db

The following items have been added:

• Collection of database backups : data/db/backups/

Motivation

The primary goal is to simplify persistent storage management, especially for Docker deployments. By grouping all operational data in one place, users only need to mount a single volume (e.g., /host/path:/app/data) to persist their database and configurations, rather than managing multiple individual mounts.

Changes

• Refactor: Created the data directory.
• Configuration: Updated internal paths and environment variables to point to the new location within data.
• Docker: Updated the Dockerfile and compose.yaml to reflect the new structure.
• Documentation: Updated the README to guide users on how to access these files.

Impact

IMPORTANT: This is a breaking change for existing installations. Users must move their existing edgemining.db and policy folder into the new data/ directory to maintain their data.