chore(automation): trim docstrings to intent only

Cut the docstrings and Field(description=...) text across the entire
automations/ tree down to single-line intent statements, matching the
multi_agent_chat conciseness style:

- Module docstrings: one line stating what the file is.
- Class docstrings: deleted when the class name + module docstring
  already cover intent; kept only where they add a constraint or
  rationale not visible in the signature.
- Pydantic Field descriptions: short noun phrases / clauses, not
  full sentences. Reasoning that belonged in the design plan moved
  out of the code.
- Enum values: per-value docstrings replaced with terse inline
  comments where the meaning isn't obvious from the name.

Behaviour is unchanged. The same 33 files, same public surface, same
imports — verified by re-running the 10-point registry smoke test and
the 8-point schema round-trip / constraint suite from commits 9 and
10.

LOC: 1180 → 691 (-42%).

surfsense_backend/app/automations/persistence/enums/automation_status.py

@@ -1,4 +1,4 @@
-"""``AutomationStatus`` — lifecycle of a stored automation definition."""
+"""Automation lifecycle status."""
 
 from __future__ import annotations
 
@@ -6,13 +6,6 @@ from enum import StrEnum
 
 
 class AutomationStatus(StrEnum):
-    """Status of an automation in the registry.
-
-    ``active``   — eligible to fire from its triggers.
-    ``paused``   — definition retained, triggers do not fire.
-    ``archived`` — kept for run history only; no edits, no fires.
-    """
-
-    ACTIVE = "active"
-    PAUSED = "paused"
-    ARCHIVED = "archived"
+    ACTIVE = "active"  # eligible to fire
+    PAUSED = "paused"  # kept, but triggers don't fire
+    ARCHIVED = "archived"  # read-only history