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/schemas/definition/execution.py

@@ -1,4 +1,4 @@
-"""``ExecutionBlock`` — the ``execution`` section of the automation definition."""
+"""``ExecutionBlock`` — automation-wide execution defaults (overridable per step)."""
 
 from __future__ import annotations
 
@@ -10,67 +10,16 @@ from .plan_step import PlanStep
 
 
 class ExecutionBlock(BaseModel):
-    """The ``execution`` block of an ``AutomationDefinition``.
-
-    Carries automation-wide defaults that individual ``PlanStep``s
-    can override. Every field has a sane default so an automation
-    definition may omit the block entirely; in that case all defaults
-    apply.
-
-    ``on_failure`` is a secondary plan that runs only when the main
-    ``plan`` fails after retries exhaust. It uses the same
-    ``PlanStep`` shape as the main plan and shares the same execution
-    semantics.
-    """
-
     model_config = ConfigDict(extra="forbid")
 
-    timeout_seconds: int = Field(
-        default=600,
-        gt=0,
-        description=(
-            "Hard wall-clock cap for the entire run. The executor "
-            "transitions the run to ``timed_out`` when this is "
-            "exceeded."
-        ),
-    )
-    max_retries: int = Field(
-        default=2,
-        ge=0,
-        description=(
-            "Per-step retry budget applied when a step raises a "
-            "retryable error. Steps may override per-step."
-        ),
-    )
-    retry_backoff: Literal["exponential", "linear", "none"] = Field(
-        default="exponential",
-        description="Backoff policy between retries.",
-    )
-    concurrency: Literal[
-        "drop_if_running", "queue", "always"
-    ] = Field(
-        default="drop_if_running",
-        description=(
-            "Behaviour when a new fire arrives while a previous run "
-            "is still in progress. ``drop_if_running`` skips the new "
-            "fire, ``queue`` enqueues it, ``always`` runs it in "
-            "parallel."
-        ),
-    )
+    timeout_seconds: int = Field(default=600, gt=0, description="Wall-clock cap for the run.")
+    max_retries: int = Field(default=2, ge=0, description="Per-step retry budget.")
+    retry_backoff: Literal["exponential", "linear", "none"] = "exponential"
+    concurrency: Literal["drop_if_running", "queue", "always"] = "drop_if_running"
     budget_cap_usd: float | None = Field(
-        default=None,
-        gt=0,
-        description=(
-            "Optional mid-flight cost cap in USD. The executor kills "
-            "the run when accumulated cost exceeds this value. v1 "
-            "treats this as an advisory because cost tracking lands "
-            "with the executor in a later step."
-        ),
+        default=None, gt=0, description="Kill the run when accumulated cost exceeds this."
     )
     on_failure: list[PlanStep] = Field(
         default_factory=list,
-        description=(
-            "Secondary plan executed only when the main plan fails "
-            "after retries exhaust. Empty list means no fallback."
-        ),
+        description="Steps run when the main plan fails after retries.",
     )