chore: add ahtml evaluation assets, templates, rubric and test cases

Add new static assets for agent-html UI, plus full evaluation suite for ahtml skill including:
- results template for student run records
- official grading rubric
- skill evaluation criteria document
- complete evals.json with 4 evaluation layers and scenarios

Author: Sayhi-bzb

.agents/skills/agent-html/references/examples.md

@@ -18,6 +18,7 @@ Use the closest valid fixture before inventing new structure.
 - `minimal-page.xml`
 - `section-width.xml`
 - `text-basic.xml`
+- `timeline-basic.xml`
 
 ## Invalid Patterns
 
@@ -35,5 +36,9 @@ Use the closest valid fixture before inventing new structure.
 - `missing-tabs-trigger-value.xml`
 - `section-invalid-width.xml`
 - `text-with-child.xml`
+- `timeline-invalid-status.xml`
+- `timeline-item-missing-title.xml`
+- `timeline-missing-item.xml`
+- `timeline-unknown-icon.xml`
 - `unknown-icon-name.xml`
 - `unknown-tag.xml`

.agents/skills/agent-html/references/grammar.md

@@ -82,6 +82,12 @@
 - `TabsTrigger:value=string, disabled?="true|false" -> Text, Icon?`
 - `TabsContent:value=string -> Layout | UI | Text`
 
+- `Timeline -> TimelineItem+`
+- `TimelineItem:icon?=string, status?="default|complete|current|muted", meta?=string -> TimelineTitle, TimelineDescription?, TimelineContent?`
+- `TimelineTitle -> Text`
+- `TimelineDescription -> Text`
+- `TimelineContent -> Layout | UI | Text`
+
 - `Chart:type="area|bar" -> ChartSeries+, ChartTooltip?`
 - `ChartSeries:key=string, label?=string`
 - `ChartTooltip:hideLabel?="true|false" -> none`