Add effort badge to chain summary

Snapshot the agent's effort onto the chain (like model) so it survives
reload, archive and shared chains, then show it in the chain-end meta line.

- ChainRecord.Effort + chains.effort column (TryAddColumn migration).
- CreateChain INSERT carries the value.
- ChatService snapshots agent.Effort at chain creation, but only for Claude
  models – OpenAI providers store '' so there is no misleading badge.
- Anthropic streaming + CLI done-events include effort for the live path.
- chat.js buildMetaBadges renders "Effort: <level>" after the model badge,
  only when a value is set.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

wwwroot/js/chat.js

@@ -4,6 +4,7 @@ function buildMetaBadges(d) {
   const badges = [];
   if (d.planMode) badges.push('📋 Plan-Modus');
   badges.push(prettyModelName(d.model));
+  if (d.effort) badges.push('Effort: ' + d.effort);
   badges.push('Tokens: ' + (d.inputTokens || 0) + ' / ' + (d.outputTokens || 0));
   if (d.cacheCreationTokens > 0 || d.cacheReadTokens > 0) {
     badges.push('Cache: ' + (d.cacheReadTokens || 0) + ' / ' + (d.cacheCreationTokens || 0));