fix(skills): teach {current_user_id}, not $currentUser, in the ui Filtering example (#14781)

`skills/objectstack-ui/rules/list-views.md` taught `$currentUser` as a filter
value. No filter path resolves it: both resolvers recognise a placeholder only
when the whole value is brace-wrapped (`FILTER_TOKEN_WRAPPED_RE` in
`packages/spec/src/data/context-tokens.zod.ts`, `WHOLE_TOKEN_RE` in
`@object-ui/core`), so an unbraced `$currentUser` is not even classified as a
placeholder attempt — it reaches the data engine as a literal, matches nothing,
and the list renders empty with no diagnostic anywhere.

Rewrite the example value and its note to `{current_user_id}`, the declared
token, so the rule file agrees with the package's own
`## Date Macros — Filter Placeholders` contract in SKILL.md.

Net -4 bytes (3011 -> 3010 tokens, ceiling 3011 unchanged).


Claude-Session: https://claude.ai/code/session_01LraLgQVGq8egUwfYZpbYt1

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-litant

skills/objectstack-ui/rules/list-views.md

@@ -92,15 +92,15 @@ columns: [
 ```typescript
 filter: [
   { field: 'status', operator: 'not_equals', value: 'closed' },
-  { field: 'assigned_to', operator: 'equals', value: '$currentUser' },
+  { field: 'assigned_to', operator: 'equals', value: '{current_user_id}' },
 ]
 ```
 
 Common operators: `equals`, `not_equals`, `contains`, `starts_with`,
 `greater_than`, `less_than`, `is_empty`, `is_not_empty`, `in`, `not_in`,
 `this_week`, `this_month`, `this_quarter`, `last_n_days`.
 
-> **`$currentUser`** is a runtime variable — the logged-in user's ID.
+> **`{current_user_id}`** resolves to the signed-in user's id.
 
 ### End-User Quick Filters (`userFilters`, ADR-0047)