fix(cms): seed entryStack from originating page path in dynamic hole endpoint (#548)

[ShreyasUday]

Summary

Fixes #548 (split out from #546).

When dynamic Layer C holes are hydrated via /_instatic/hole/<nodeId>?v=<version>&u=<page-url>, renderHoleFragment in server/handlers/cms/hole.ts previously hardcoded entryStack: [].

As a result, {currentEntry.*} bindings inside dynamic hole subtrees (such as loop cell filters mixing {currentEntry.slug} and {route.query.*}) resolved to empty strings "". For example, a filter like "{currentEntry.slug}-{route.query.region}" on /courses/time-management?region=cz evaluated to "-cz", causing queries to return no records and render empty.

This change:

• Adds resolveOriginatingEntry in server/handlers/cms/hole.ts using contentRouteFromPath(pageUrl.pathname) and getPublishedDataRowByRoute to look up the published entry row.
• Seeds templateContext.entryStack with [entryRow] when an entry row matches, allowing {currentEntry.*} bindings to resolve seamlessly inside dynamic holes.
• Safely falls back to entryStack = [] if the page path is not a content entry route.

Verification

• bun run build
• bun test
• bun run lint
• Docker/deployment check, if relevant

Checklist

• Tests cover behavior changes.
• Docs were updated when behavior, config, deployment, or public surfaces changed.
• No compatibility shim was added for old pre-release behavior.
• No secrets, local databases, uploads, or generated artifacts are included.