fix: recognize [1m] suffix on all models, not just Sonnet 4.5 (#172)

The getContextConfig function was hardcoded to only match
claude-sonnet-4-5 models with the [1m] suffix. Other models like
claude-opus-4-6[1m] also support 1M context but were falling back to
the 200k default, causing incorrect context percentage display.

The [1m] suffix itself is sufficient to indicate 1M context regardless
of model family.

src/utils/__tests__/model-context.test.ts

@@ -7,7 +7,7 @@ import {
 import { getContextConfig } from '../model-context';
 
 describe('getContextConfig', () => {
-    describe('Sonnet 4.5 models with [1m] suffix', () => {
+    describe('Models with [1m] suffix', () => {
         it('should return 1M context window for claude-sonnet-4-5 with [1m] suffix', () => {
             const config = getContextConfig('claude-sonnet-4-5-20250929[1m]');
 
@@ -15,6 +15,13 @@ describe('getContextConfig', () => {
             expect(config.usableTokens).toBe(800000);
         });
 
+        it('should return 1M context window for claude-opus-4-6 with [1m] suffix', () => {
+            const config = getContextConfig('claude-opus-4-6[1m]');
+
+            expect(config.maxTokens).toBe(1000000);
+            expect(config.usableTokens).toBe(800000);
+        });
+
         it('should return 1M context window for AWS Bedrock format with [1m] suffix', () => {
             const config = getContextConfig(
                 'us.anthropic.claude-sonnet-4-5-20250929-v1:0[1m]'
@@ -32,7 +39,7 @@ describe('getContextConfig', () => {
         });
     });
 
-    describe('Sonnet 4.5 models without [1m] suffix', () => {
+    describe('Models without [1m] suffix', () => {
         it('should return 200k context window for claude-sonnet-4-5 without [1m] suffix', () => {
             const config = getContextConfig('claude-sonnet-4-5-20250929');
 

src/utils/model-context.ts

@@ -13,11 +13,8 @@ export function getContextConfig(modelId?: string): ModelContextConfig {
     if (!modelId)
         return defaultConfig;
 
-    // Sonnet 4.5 variants with 1M context (requires [1m] suffix for long context beta)
-    if (
-        modelId.includes('claude-sonnet-4-5')
-        && modelId.toLowerCase().includes('[1m]')
-    ) {
+    // Any model with [1m] suffix has 1M context
+    if (modelId.toLowerCase().includes('[1m]')) {
         return {
             maxTokens: 1000000,
             usableTokens: 800000 // 80% of 1M