Migrate STX components to current syntax (match trailbuddy)

Context

The stx components in resources/components/ use an older syntax (Alpine-style directives, $props.x access, derived(), no <template> wrapper). Trailbuddy's components use the current convention (defineProps<T>() + withDefaults, <template> wrapper, PascalCase component imports).

ts-analytics is meant to be a reference implementation of an analytics dashboard built in the Stacks/STX stack — its component code should reflect the current best practice, not legacy syntax.

Reference

• New convention: https://github.com/stacksjs/trailbuddy/tree/main/resources/components
  • e.g. FeaturedTrailCard.stx, Hero.stx
• Outdated example in this repo: resources/components/StatCard.stx

Scope

Migrate every file under resources/components/*.stx:

• EventLog.stx
• EventBar.stx
• FlowLink.stx
• InsightCard.stx
• SiteCard.stx
• StatCard.stx
• SessionModal.stx
• SessionCard.stx
• ErrorCard.stx
• (any others)

For each:

• <script client> → <script server> (or whichever fits — match trailbuddy's choice)
• $props.x → typed defineProps<T>() + withDefaults
• derived(() => ...) → idiomatic equivalent in the new syntax
• @if / @class / x-id directives → <template> wrapper + standard binding syntax
• PascalCase component references where applicable

Verification

• bun run build succeeds
• Dashboard renders with no visual regressions
• No console warnings about deprecated syntax