Add Claude 4.5 model variants (Haiku, Sonnet, Opus) to OpenRouter client (#1254)

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## Motivation and Context
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#1199 (comment)
A user asked to add Claude 4.5 Opus to the list of OpenRouter models.

## Breaking Changes
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#### Type of the changes
- [x] New feature (non-breaking change which adds functionality)
- [ ] Bug fix (non-breaking change which fixes an issue)
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- [ ] Documentation update
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- [ ] Refactoring

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- [x] The pull request has a description of the proposed change
- [x] I read the [Contributing
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Author: aozherelyeva

prompt/prompt-executor/prompt-executor-clients/prompt-executor-openrouter-client/src/commonMain/kotlin/ai/koog/prompt/executor/clients/openrouter/OpenRouterModels.kt

@@ -137,6 +137,42 @@ public object OpenRouterModels : LLModelDefinitions {
         maxOutputTokens = 32_000,
     )
 
+    /**
+     * Claude Haiku 4.5 is Anthropic’s fastest and most efficient model,
+     * delivering near-frontier intelligence at a fraction of the cost and latency of larger Claude models.
+     */
+    public val Claude4_5Haiku: LLModel = LLModel(
+        provider = LLMProvider.OpenRouter,
+        id = "anthropic/claude-haiku-4.5",
+        capabilities = multimodalCapabilities + additionalCapabilities,
+        contextLength = 200_000,
+        maxOutputTokens = 64_000,
+    )
+
+    /**
+     * Claude Sonnet 4.5 is Anthropic’s most advanced Sonnet model to date, optimized for real-world agents
+     * and coding workflows.
+     */
+    public val Claude4_5Sonnet: LLModel = LLModel(
+        provider = LLMProvider.OpenRouter,
+        id = "anthropic/claude-sonnet-4.5",
+        capabilities = multimodalCapabilities + additionalCapabilities,
+        contextLength = 1_000_000,
+        maxOutputTokens = 64_000,
+    )
+
+    /**
+     * Claude Opus 4.5 is Anthropic’s frontier reasoning model optimized for complex software engineering,
+     * agentic workflows, and long-horizon computer use.
+     */
+    public val Claude4_5Opus: LLModel = LLModel(
+        provider = LLMProvider.OpenRouter,
+        id = "anthropic/claude-opus-4.5",
+        capabilities = multimodalCapabilities + additionalCapabilities,
+        contextLength = 200_000,
+        maxOutputTokens = 32_000,
+    )
+
     /**
      * Represents the GPT-4o-mini model hosted on OpenRouter.
      *