Migrate declarative configs to config/ dir and remove hardcoded paths

Replace all hardcoded /home/wall/vacuum-wall paths in lib/ with Path(__file__).resolve()
auto-discovery. Move config files from data/ to config/<subsystem>/config.json.
ACME now uses ACME_HOME env var and data/acme/ for cert storage. Systemd units
and sudoers use {{ USER_NAME }}, {{ PROJECT_DIR }}, {{ ACME_HOME }} Jinja2
template variables for install-time substitution. Remove sys.path.insert boot
strap from test files.

tests/test_wireguard.py

@@ -1,12 +1,9 @@
 import json
-import sys
 from pathlib import Path
 from unittest.mock import MagicMock, patch
 
 import pytest
 
-sys.path.insert(0, "/home/wall/vacuum-wall")
-
 from lib import wireguard