Advisory issues read as advice rather than failure

`ADVISORY_ISSUES` moves next to `ValidationIssue` in pipeline.py, and the
model derives an `advisory` flag from its own code, so the distinction the
engine already made ships to the client instead of being re-guessed there.

The dock keeps its summary in `--destructive` only when a real fault is
among the issues and paints an advisory row `--muted-foreground`; the
canvas leaves advisories off a node's dot and border entirely, since node
status has three colours and no warning tier.

biome checks the generated `openapi.json`, which nothing formats since the
SDK script dropped its format pass — ignore it like the other generated
files.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013Gf7WaExcJ9bs3kfJXB3nK

backend/fluksio/flow/pipeline.py

@@ -25,7 +25,7 @@ from concurrent.futures import Future, ThreadPoolExecutor, wait
 from contextlib import contextmanager
 from typing import Any, Literal, Protocol
 
-from pydantic import BaseModel
+from pydantic import BaseModel, computed_field
 
 from fluksio.flow import logs
 from fluksio.flow.artifacts import is_reference
@@ -41,9 +41,15 @@ logger = logging.getLogger(__name__)
 #: manual run shows up in the history — but it is no one's idempotency key.
 MANUAL_RUN_PREFIX = "manual-"
 
+# Validation codes that are worth saying but do not stop a flow running, so
+# neither the brain graph nor the health summary treats them as a fault.
+# Lives here rather than beside the controller so `ValidationIssue` can carry
+# the distinction itself, and every reader gets it for free.
+ADVISORY_ISSUES = frozenset({"unauthenticated_hook"})
+
 
 class ValidationIssue(BaseModel):
-    """A problem that keeps a flow from running correctly."""
+    """Something wrong with a flow — a fault, or merely advisory."""
 
     code: Literal[
         "cycle",
@@ -60,6 +66,12 @@ class ValidationIssue(BaseModel):
     port: str | None = None
     message_name: str | None = None
 
+    @computed_field  # type: ignore[prop-decorator]
+    @property
+    def advisory(self) -> bool:
+        """Worth saying, but not a fault — the UI says so in a softer tone."""
+        return self.code in ADVISORY_ISSUES
+
 
 class ValueSource(BaseModel):
     """Who caused a message to take its current value.