Spike Compose source names for layout trees

[static-var]

Summary

• add research spike for enriching experimental layoutTree nodes with composable/source names
• add Android probe for Compose tooling composition data
• add CMP Android-target probe for the same approach
• document feasibility, risks, correlation strategy, and recommended production shape

Key findings

• Compose tooling data can expose composable names such as Column, Row, Button, Card, and custom composables
• source file/line information is available when Compose source information is present
• NodeGroup.node can be the actual runtime LayoutNode, enabling identity correlation
• named call groups are often separate from node groups, so production should correlate by node identity first, then nearest named/source ancestor, then fallback to bounds/order
• APIs are tooling/internal/high-risk and should be used only as nullable best-effort enrichment

Verification

• build-brief ./gradlew spotlessCheck detekt :plugin:test :preview-scanner:test
• ANDROID_HOME=$HOME/Library/Android/sdk build-brief spikes/renderer-android-compose/gradlew -p spikes/renderer-android-compose :app:testDebugUnitTest --tests dev.staticvar.agentpreview.spike.CompositionToolingDataProbeTest
• ANDROID_HOME=$HOME/Library/Android/sdk build-brief spikes/renderer-cmp-compose/gradlew -p spikes/renderer-cmp-compose :composeApp:testDebugUnitTest --tests dev.staticvar.agentpreview.cmp.CmpCompositionToolingDataProbeTest

Review

• Implementation delegated to subagent
• Separate review subagent approved with no blocking findings

No production schema/runtime changes in this spike.