docs(skills): English-only audit + cross-link compareTo/categoryGranularity

* skills/objectstack-ui/SKILL.md: drop Chinese 较上期/较去年/较前7天
  examples from the compareTo metric paragraph (per English-only rule)
  and rephrase to describe the i18n labels generically.

* skills/objectstack-query/SKILL.md: enrich the CRM Analytics Query
  Blueprint table — the 'KPI widgets' row now mentions compareTo, and
  the 'Time-series chart' row replaces the vague 'month bucketing'
  phrasing with an enumeration of the categoryGranularity options and
  the requirement to do bucketing server-side.

* skills/objectstack-query/rules/aggregation.md: prefix the LAG/LEAD
  period-over-period example with a callout pointing dashboard authors
  to the higher-level compareTo widget field, so they don't reach for
  raw window functions when a one-line modifier exists.

Audit scope: scanned all 41 skill .md files for stray non-English
content and dashboard/chart/KPI references that should mention the new
compareTo + categoryGranularity fields. objectstack-i18n keeps its
Chinese / multi-locale strings — they are the documented translation
bundle examples and are appropriate content for that skill.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: os-zhuang

skills/objectstack-query/SKILL.md

@@ -528,8 +528,8 @@ Use dashboards/reports metadata as the practical query pattern source:
 
 | Query Need | CRM Reference | Pattern |
 |:--|:--|:--|
-| KPI widgets | `dashboards/sales.dashboard.ts` | Filtered aggregates (`sum`, `count`, `avg`) over `opportunity` |
-| Time-series chart | `dashboards/sales.dashboard.ts` | Date filters + month bucketing for trend analysis |
+| KPI widgets | `dashboards/sales.dashboard.ts` | Filtered aggregates (`sum`, `count`, `avg`) over `opportunity`. Add `compareTo: 'previousPeriod' \| 'previousYear'` on the widget for a one-line period-over-period delta. |
+| Time-series chart | `dashboards/sales.dashboard.ts` | Date filters + `categoryGranularity: 'day' \| 'week' \| 'month' \| 'quarter' \| 'year'` for server-side bucketing — never bucket by hand on the client. Pair with `compareTo` for an aligned YoY overlay. |
 | Matrix report | `reports/opportunity.report.ts` | `groupingsDown` + `groupingsAcross` + `dateGranularity: 'quarter'` |
 | Funnel summary | `reports/opportunity.report.ts` | Multi-level grouping (`owner -> stage`) + aggregated measures |
 | Operational filter | dashboard/report filters | Prefer declarative operators (`$ne`, `$nin`, `$gte`) over hardcoded SQL |

skills/objectstack-query/rules/aggregation.md

@@ -177,6 +177,14 @@ Window functions compute values across row sets WITHOUT collapsing results.
 
 ### LAG / LEAD (Period-over-Period)
 
+> **For dashboard widgets**, prefer the higher-level `compareTo:
+> 'previousPeriod' | 'previousYear' | { offset }` field on the widget
+> schema (see *objectstack-ui* → *Period-over-period — `compareTo`*).
+> The renderer issues the shifted query for you and aligns the result
+> bucket-for-bucket with `categoryGranularity`. Reach for the raw
+> `lag` / `lead` window functions below when you need the comparison
+> in a custom query result (reports, ad-hoc SQL, cube measures).
+
 ```typescript
 // Month-over-month comparison
 {

skills/objectstack-ui/SKILL.md

@@ -494,10 +494,10 @@ no second `filter` is required.
 
 * **Metric widgets** — the prior-period value renders as a small caption
   beneath the headline number, alongside a green/red delta arrow and an
-  i18n label (`较上期` / `vs previous period`, `较去年` / `vs last year`,
-  `较前7天` / `vs previous 7d`, etc.). Authors should *not* hand-author
-  `options.trend` when `compareTo` is set; the renderer wins and overwrites
-  it.
+  i18n trend label resolved from the comparison kind (e.g. `vs previous
+  period`, `vs previous year`, `vs previous 7d`). Authors should *not*
+  hand-author `options.trend` when `compareTo` is set; the renderer wins
+  and overwrites it.
 * **Cartesian charts** (`line` / `area` / `bar` / `horizontal-bar` /
   `scatter`) — the comparison series is appended after the primary series
   with `variant: 'comparison'` and styled as a muted overlay (`opacity: 0.5`