feat: v0.3.0 - fix provider data loss, oauth corruption & switch UX

Bug fixes:
- Fix config.toml wiped to single provider on switch (now writes all providers)
- Fix managed:kimi-code oauth key corruption (oauth/kimi-code was rewritten
  to oauth/managed-kimi-code, breaking the official subscription)
- Fix default_model not switching due to React 18 deferred state update
  (updateConfig now sets configRef synchronously before setConfig)
- Strip KimiSwitch-private default_model from config.toml provider output

Architecture:
- config.toml is now the authoritative source for Kimi Code provider data
- SQLite stores only metadata (notes, official URLs, remembered models)
- Load reconciles config.toml with SQLite for external /provider changes
- Activate is a no-op for KimiCode (save already writes config.toml)

Features:
- Selected provider moves to top of list on switch
- Add models-dev context size lookup
- Add tauri-plugin-single-instance

Tests:
- 3 new regression tests: oauth key round-trip, all-providers write,
  private default_model strip

src/components/ProviderEdit.tsx

@@ -3,6 +3,7 @@ import { invoke } from "@tauri-apps/api/core";
 import { useTranslation } from "../i18n";
 import type { TranslationKey } from "../i18n/zh";
 import { getDefaultMaxContextSize } from "../lib/model-defaults";
+import { capabilitiesFromRef, getModelRef } from "../lib/models-dev";
 import { AgentSettingsPanel } from "./AgentSettingsPanel";
 import type { Agent, DiscoveredModel, Model, Provider, ProviderType } from "../types";
 
@@ -400,15 +401,24 @@ function ModelMapping({
     for (const dm of discovered) {
       if (!selected.has(dm.id)) continue;
       const alias = dm.id.replace(/[^a-zA-Z0-9_-]/g, "-");
-      const max_context_size = dm.max_context_size ?? getDefaultMaxContextSize(dm.id);
+      const ref = getModelRef(dm.id);
+      // Priority: API-provided value > models.dev reference > regex fallback
+      const max_context_size =
+        dm.max_context_size ?? ref?.context ?? getDefaultMaxContextSize(dm.id);
       toAdd.push({
         alias,
         provider: provider.name,
         model: dm.id,
         max_context_size,
-        display_name: dm.display_name,
+        display_name: dm.display_name ?? ref?.name ?? null,
         supports_1m: max_context_size >= 1_000_000,
-        capabilities: fetchThinking ? ["thinking"] : [],
+        // Reference data wins when available; otherwise keep the old
+        // fetchThinking-checkbox behavior as the fallback.
+        capabilities: ref
+          ? capabilitiesFromRef(ref)
+          : fetchThinking
+            ? ["thinking"]
+            : [],
       });
     }
     onBulkAdd(toAdd);