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/metadata.py

@@ -1,4 +1,4 @@
-"""``MetadataBlock`` — the ``metadata`` section of the automation definition."""
+"""``MetadataBlock`` — free-form metadata on a definition. Extra keys allowed."""
 
 from __future__ import annotations
 
@@ -6,31 +6,9 @@ from pydantic import BaseModel, ConfigDict, Field
 
 
 class MetadataBlock(BaseModel):
-    """Free-form metadata attached to the automation definition.
-
-    Unlike the rest of the envelope this block tolerates unknown keys
-    (``extra='allow'``) — it's a deliberate extension point for
-    UI annotations, NL-generator breadcrumbs, custom tags, etc.
-
-    Two fields are first-class so the rest of the system can rely on
-    them without reaching into the loose extras:
-
-    ``tags`` — used by the UI for filtering and grouping.
-    ``created_from_nl`` — set by the NL generator so we can later
-    measure how many runs came from natural-language authoring.
-    """
-
     model_config = ConfigDict(extra="allow")
 
-    tags: list[str] = Field(
-        default_factory=list,
-        description="UI-facing tags. No semantic meaning to the engine.",
-    )
+    tags: list[str] = Field(default_factory=list)
     created_from_nl: bool = Field(
-        default=False,
-        description=(
-            "True when the definition was produced by the NL "
-            "generator (set automatically by the generator path; "
-            "human-authored definitions keep this false)."
-        ),
+        default=False, description="True when produced by the NL generator."
     )