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/run_status.py

@@ -1,4 +1,4 @@
-"""``RunStatus`` — the state machine of a single ``AutomationRun``."""
+"""AutomationRun state machine: pending → running → (succeeded|failed|cancelled|timed_out)."""
 
 from __future__ import annotations
 
@@ -6,20 +6,6 @@ from enum import StrEnum
 
 
 class RunStatus(StrEnum):
-    """Lifecycle states of an ``AutomationRun`` row.
-
-    Transitions are linear with three terminal branches:
-
-        pending → running → (succeeded | failed | cancelled | timed_out)
-
-    ``pending``    — row created, executor task enqueued, work not started.
-    ``running``    — executor has picked up the run.
-    ``succeeded``  — terminal: plan completed without error.
-    ``failed``     — terminal: at least one step raised an unrecoverable error.
-    ``cancelled``  — terminal: caller asked for cancellation.
-    ``timed_out``  — terminal: run exceeded its configured timeout.
-    """
-
     PENDING = "pending"
     RUNNING = "running"
     SUCCEEDED = "succeeded"