skills(data): drop the two bare ADR-0010 citations (net -51 bytes / -13 tokens)

`skills/objectstack-data/SKILL.md` carried two bare `ADR-0010` citations. The
number is claimed by two unrelated records (`0010-metadata-protection-model`
and `0010-nl-to-flow-authoring`, frozen in `check-adr-anchors.mjs`'s
`KNOWN_NUMBER_COLLISIONS`), and the published catalog ships into codebases with
no `docs/adr/` to grep, so neither site resolved for its actual audience.

- The `reason:` string in the `sys_user` protection example is authored
  metadata that ships in a customer's own code, where no later pass over this
  repo can reach it. It drops `— see ADR-0010.`; the rest of the reason and
  the adjacent `docsUrl` — a public page that does resolve — both stay.
- The prose sentence `See ADR-0010 for the full model.` is dropped: the
  section heading (`Metadata Protection`) and the sentence before it already
  name the model, so the citation's only unique content was a pointer the
  reader cannot open.

Both edits are deletions, so the shrink-only token ratchet is satisfied inside
the file: 10009 -> 9996 against a 10009 ceiling. The five `ADR-0019` sites and
the generator-owned `references/_index.md` mentions were examined and left
untouched — context selects the record at all of them.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LraLgQVGq8egUwfYZpbYt1

Author: claude

skills/objectstack-data/SKILL.md

@@ -564,7 +564,6 @@ it, and `defineStack` errors unless the grant declares
 ## Metadata Protection (`protection`)
 
 Package authors can lock shipped metadata against Studio edits / overlays / deletes.
-See ADR-0010 for the full model.
 
 The `protection` block is **declared on the source schema** (`*.object.ts`,
 `*.app.ts`, `*.view.ts`, …) and stripped at load time — it never appears in
@@ -608,7 +607,7 @@ export const SysUserObject = ObjectSchema.create({
   sharingModel: 'public_read',
   protection: {
     lock: 'full',
-    reason: 'Core identity object — see ADR-0010.',
+    reason: 'Core identity object',
     docsUrl: 'https://objectstack.ai/docs/references/shared/protection',
   },
   fields: { username: { type: 'text', required: true } },