feat: multi-provider model configuration with UI/UX improvements (#355)

* feat: add multi-provider model configuration

- Add model config dialog for managing multiple AI providers
- Support for OpenAI, Anthropic, Google, Azure, Bedrock, OpenRouter, DeepSeek, SiliconFlow, Ollama, and AI Gateway
- Add model selector dropdown in chat panel header
- Add API key validation endpoint
- Add custom model ID input with keyboard navigation
- Fix hover highlight in Command component
- Add suggested models for each provider including latest Claude 4.5 series
- Store configuration locally in browser

* feat: improve model config UI and move selector to chat input

- Move model selector from header to chat input (left of send button)
- Add per-model validation status (queued, running, valid, invalid)
- Filter model selector to only show verified models
- Add editable model IDs in config dialog
- Add custom model input field alongside suggested models dropdown
- Fix hover states on provider buttons and select triggers
- Update OpenAI suggested models with GPT-5 series
- Add alert-dialog component for delete confirmation

* refactor: revert shadcn component changes, apply hover fix at usage site

* feat: add AWS credentials support for Bedrock provider

- Add AWS Access Key ID, Secret Access Key, Region fields for Bedrock
- Show different credential fields based on provider type
- Update validation API to handle Bedrock with AWS credentials
- Add region selector with common AWS regions

* fix: reset Test button after validation completes

* fix: reset validation button to Test after success

* fix: complete bedrock support and UI/UX improvements

- Add bedrock to ALLOWED_CLIENT_PROVIDERS for client credentials
- Pass AWS credentials through full chain (headers → API → provider)
- Replace non-existent GPT-5 models with real ones (o1, o3-mini)
- Add accessibility: aria-labels, focus-visible rings, inline errors
- Add more AWS regions (Ohio, London, Paris, Mumbai, Seoul, São Paulo)
- Fix setTimeout cleanup with useRef on component unmount
- Fix TypeScript type consistency in getSelectedAIConfig fallback

* chore: remove unused code

- Remove unused setAccessCodeRequired state in chat-panel.tsx
- Remove unused getSelectedModel export in model-config.ts

* fix: UI/UX improvements for model configuration dialog

- Add gradient header styling with icon badge
- Change Configuration section icon from Key to Settings2
- Add duplicate model detection with warning banner and inline removal
- Filter out already-added models from suggestions dropdown
- Add type-to-confirm for deleting providers with 3+ models
- Enhance delete confirmation dialog with warning icon
- Improve model selector discoverability (show model name + chevron)
- Add truncation for long model names with title tooltip
- Remove AI provider settings from Settings dialog (now in Model Config)
- Extract ValidationButton into reusable component

* fix: prevent duplicate model IDs within same provider

- Block adding model if ID already exists in provider
- Block editing model ID to match existing model in provider

* fix: improve duplicate model ID notifications

- Add toast notification when trying to add duplicate model
- Allow free typing when editing model ID, validate on blur
- Show warning toast instead of blocking input

* fix: improve duplicate model validation UX in config dialog

- Add inline error display for duplicate model IDs
- Show red border on input when error exists
- Validate on blur with shake animation for edit errors
- Prevent saving empty model names
- Clear errors when user starts typing
- Simplify error styling (small red text, no heavy chips)

lib/ai-providers.ts

@@ -33,6 +33,11 @@ export interface ClientOverrides {
     baseUrl?: string | null
     apiKey?: string | null
     modelId?: string | null
+    // AWS Bedrock credentials
+    awsAccessKeyId?: string | null
+    awsSecretAccessKey?: string | null
+    awsRegion?: string | null
+    awsSessionToken?: string | null
 }
 
 // Providers that can be used with client-provided API keys
@@ -41,6 +46,7 @@ const ALLOWED_CLIENT_PROVIDERS: ProviderName[] = [
     "anthropic",
     "google",
     "azure",
+    "bedrock",
     "openrouter",
     "deepseek",
     "siliconflow",
@@ -537,12 +543,25 @@ export function getAIModel(overrides?: ClientOverrides): ModelConfig {
 
     switch (provider) {
         case "bedrock": {
-            // Use credential provider chain for IAM role support (Lambda, EC2, etc.)
-            // Falls back to env vars (AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY) for local dev
-            const bedrockProvider = createAmazonBedrock({
-                region: process.env.AWS_REGION || "us-west-2",
-                credentialProvider: fromNodeProviderChain(),
-            })
+            // Use client-provided credentials if available, otherwise fall back to IAM/env vars
+            const hasClientCredentials =
+                overrides?.awsAccessKeyId && overrides?.awsSecretAccessKey
+            const bedrockRegion =
+                overrides?.awsRegion || process.env.AWS_REGION || "us-west-2"
+
+            const bedrockProvider = hasClientCredentials
+                ? createAmazonBedrock({
+                      region: bedrockRegion,
+                      accessKeyId: overrides.awsAccessKeyId!,
+                      secretAccessKey: overrides.awsSecretAccessKey!,
+                      ...(overrides?.awsSessionToken && {
+                          sessionToken: overrides.awsSessionToken,
+                      }),
+                  })
+                : createAmazonBedrock({
+                      region: bedrockRegion,
+                      credentialProvider: fromNodeProviderChain(),
+                  })
             model = bedrockProvider(modelId)
             // Add Anthropic beta options if using Claude models via Bedrock
             if (modelId.includes("anthropic.claude")) {