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.

daemon/handlers/common.py

@@ -0,0 +1,26 @@
+"""Shared helpers for daemon handlers."""
+
+from typing import Any
+
+from daemon.server import refresh_state
+from lib.sync import SyncEvent, bus
+
+
+def emit_and_refresh(
+    subsystem: str, payload: dict[str, Any] | None = None
+) -> list[str]:
+    """Emit a ``config_saved`` sync event and refresh the affected state.
+
+    All mutation handlers end with the same tail: emit the event, refresh
+    the source subsystem plus every subsystem the sync touched.
+
+    Args:
+        subsystem: Source subsystem name.
+        payload: Event payload (e.g. ``{"action": "zone_created"}``).
+
+    Returns:
+        Subsystems affected by the sync event.
+    """
+    sync_result = bus.emit(SyncEvent(subsystem, "config_saved", payload or {}))
+    refresh_state([subsystem, *sync_result.affected_subsystems])
+    return sync_result.affected_subsystems