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.

lib/nginx.py

@@ -12,10 +12,11 @@ from pathlib import Path
 
 from jinja2 import Environment, FileSystemLoader
 
-PROJECT_DIR = Path("/home/wall/vacuum-wall")
+PROJECT_DIR = Path(__file__).resolve().parent.parent
+CONFIG_DIR = PROJECT_DIR / "config" / "nginx"
 DATA_DIR = PROJECT_DIR / "data" / "nginx"
 SITES_DIR = DATA_DIR / "sites-enabled"
-CONFIG_FILE = DATA_DIR / "config.json"
+CONFIG_FILE = CONFIG_DIR / "config.json"
 INCLUDE_FILE = Path("/etc/nginx/conf.d/vacuum-wall.conf")
 SSL_SNIPPET = Path("/etc/nginx/snippets/vacuum-wall-ssl.conf")
 HTPASSWD_FILE = DATA_DIR / ".htpasswd"
@@ -53,6 +54,7 @@ DEFAULT_CONFIG = {
 
 
 def _ensure_dirs():
+    CONFIG_DIR.mkdir(parents=True, exist_ok=True)
     SITES_DIR.mkdir(parents=True, exist_ok=True)
 
 
@@ -178,13 +180,15 @@ def generate_server_conf(domain_cfg: dict) -> str:
         cert=domain_cfg.get("cert"),
         auth=domain_cfg.get("auth"),
         is_management=False,
+        acme_home=str(PROJECT_DIR / "data" / "acme"),
+        certs_dir=str(PROJECT_DIR / "data" / "certs"),
     )
 
 
 def _generate_management_conf(management: dict) -> str:
     tmpl = ENV.get_template("nginx/server_block.conf")
     return tmpl.render(
-        domain=management.get("domain", "wall.lan"),
+        domain=management.get("domain"),
         backend=dict(
             management.get("backend", {}), host="127.0.0.1", port=9090, proto="http"
         ),
@@ -193,6 +197,8 @@ def _generate_management_conf(management: dict) -> str:
         cert=None,
         auth=management.get("auth"),
         is_management=True,
+        acme_home=str(PROJECT_DIR / "data" / "acme"),
+        certs_dir=str(PROJECT_DIR / "data" / "certs"),
     )