ai: composer chip inherits active config's reasoning default

Pulls the reasoning storage out of ai.tsx and into the shared
llm-configs.ts helpers so Settings → LLM and the /ai composer
coordinate via one localStorage key (crema.ai.reasoning):

- loadActiveReasoning / saveActiveReasoning: read/write helpers.
- subscribeActiveReasoning: dispatches a CustomEvent on writes
  (same-tab) plus a storage-event listener (cross-tab), so the
  chip updates live when the operator stars a different config in
  another tab or in the settings panel.

Wiring:
- Settings panel onMakeActive() now also calls
  saveActiveReasoning(c.reasoning_effort ?? "off"). Starring a
  config seeds the chip with that config's default.
- /ai chip useEffect subscribes to changes; a star in Settings
  while /ai is open flips the chip in real time.
- resetAndClear no longer wipes reasoningEffort. Clearing the
  conversation shouldn't silently undo the operator's stated
  intent for thinking-mode (which is bound to their active config,
  not to the conversation).

Net behaviour:
- Star a config with reasoning_effort=medium → chip on /ai shows
  THINK MEDIUM next time you visit (or immediately if /ai is open).
- Cycle the chip while on /ai → just an override for the current
  conversation, not back-propagated to the saved config.
- Edit the config in Settings to change its default → propagates to
  the chip on next star (intentional — direct edits don't auto-
  re-activate).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

app/components/settings/llm-configurations-panel.tsx

@@ -52,6 +52,7 @@ import {
   getUsageSummary,
   listConfigurations,
   REASONING_EFFORTS,
+  saveActiveReasoning,
   updateConfiguration,
   type CatalogEntry,
   type LlmConfiguration,
@@ -134,6 +135,10 @@ export function LlmConfigurationsPanel() {
       baseURL: c.base_url || undefined,
       secretName: c.secret_name || undefined,
     })
+    // Inherit this config's reasoning default. The /ai composer chip
+    // listens for this and updates live; if the operator already
+    // override it via the chip, the next save propagates here.
+    saveActiveReasoning(c.reasoning_effort ?? "off")
     setActive(loadActiveSettings())
   }