refactor: daemon collectors, thin webui proxies, pure config reads

- move state collectors from lib/state.py to daemon/collectors/ (7
  modules, registration side-effect; daemon/server.py imports the
  package before the first populate())
- webui/api: new daemon_route() decorator factory in common.py
  collapses the try/except daemon-proxy boilerplate in all 8
  blueprints (rules/params/body/transform keep responses identical)
- firewall: interface-coverage invariant — config is the source of
  truth for zone interfaces (absent key = empty, no hands-off
  zones); pure validate_coverage() enforced at save (400) and apply
  (409, force: true overrides), top-level `unmanaged` exemption
- lib: get_config() reads are now pure (no dir creation or writes);
  new lib/bootstrap.py creates runtime dirs and persists the
  one-shot nginx legacy migration at daemon start, after
  system_import (lib.nginx.migrate_config_file)
- lib/common: compute_pending() apply-bookkeeping helper
- daemon: emit_and_refresh() handler helper; refresh_state(bump=) so
  /status/refresh no longer bumps versions (poll/mutation only)
- acme: move --log last so acme.sh never treats a real arg as the
  log-file argument
- docs: AGENTS.md, config.md, state-model.md, api.md updated;
  HARDEN.md dropped (plan implemented); apply-confirm force wording

Tests: 917 passed; ruff check + format clean.

lib/network.py

@@ -8,6 +8,7 @@ import contextlib
 import ipaddress
 import json
 import logging
+from copy import deepcopy
 from pathlib import Path
 from typing import Any
 
@@ -78,13 +79,16 @@ __all__ = [
 def get_config() -> dict[str, Any]:
     """Read network config from config/network/config.json.
 
+    Pure read — never writes. Returns the in-memory default when the file
+    is missing; the file is materialized on the first ``save_config``.
+
     Returns:
         Dict with ``interfaces`` mapping interface names to config entries.
     """
-    if not CONFIG_FILE.exists():
-        CONFIG_DIR.mkdir(parents=True, exist_ok=True)
-        save_json(CONFIG_FILE, DEFAULT_CONFIG, indent=2)
-    return load_json(CONFIG_FILE)
+    raw = load_json(CONFIG_FILE)
+    if not raw:
+        return deepcopy(DEFAULT_CONFIG)
+    return raw
 
 
 def save_config(cfg: dict[str, Any]) -> None: