docs(metadata-protocol): narrow the scope lead-in sentence, per PM review

The lead-in sentence added in the previous commit said the section
documents the function's "full internal surface" -- overclaiming: the
JSDoc is also missing cli.mdx's flow-conflict-refused row, which IS
internal to the function (not CLI-caller-dependent), so "full" did not
hold. Narrowed the claim to what is actually demonstrated (the
flow-no-engine bullet specifically), and pointed the residual
scope-split question at the follow-up decision card (#9271) the PM
filed for it, rather than implying this sentence explains every gap
between the two lists.

Fixes #9196

Author: claude

packages/metadata-protocol/src/protocol.ts

@@ -13090,10 +13090,13 @@ export class ObjectStackProtocolImplementation implements
      *
      * ## What it declines to touch, and says so
      *
-     * This section documents the function's full internal surface, including
-     * paths no CLI caller can reach: `os migrate meta --stored` always passes
-     * its own automation engine (see `canonicalizeFlow` above), so the first
-     * bullet below is never observed from that door.
+     * This section documents the function's internal surface, which is not
+     * always identical to what an operator running the CLI can observe:
+     * `os migrate meta --stored` always passes its own automation engine
+     * (see `canonicalizeFlow` above), so the first bullet below is never
+     * observed from that door. That does not by itself account for every
+     * difference between this list and `content/docs/deployment/cli.mdx`'s
+     * decline table — see #9271.
      *
      * - **`flow` rows with no reachable automation engine.** Flow-node
      *   conversions carry ADR-0078's open-namespace conflict guard, which