refactor(ipuaro): simplify LLM integration with pure XML tool format

Refactor OllamaClient to use pure XML format for tool calls as
designed in CONCEPT.md. Removes dual system (Ollama native tools +
XML parser) in favor of single source of truth (ResponseParser).

Changes:
- Remove tools parameter from ILLMClient.chat() interface
- Remove convertTools(), convertParameters(), extractToolCalls()
- Add XML format instructions to system prompt with examples
- Add CDATA support in ResponseParser for multiline content
- Add tool name validation with helpful error messages
- Move ToolDef/ToolParameter to shared/types/tool-definitions.ts

Benefits:
- Simplified architecture (single source of truth)
- CONCEPT.md compliance (pure XML as designed)
- Better validation (early detection of invalid tools)
- Reduced complexity (fewer format conversions)

Tests: 1444 passed (+4 new tests)
Coverage: 97.83% lines, 91.98% branches, 99.16% functions

packages/ipuaro/src/domain/services/ILLMClient.ts

@@ -1,26 +1,6 @@
 import type { ChatMessage } from "../value-objects/ChatMessage.js"
 import type { ToolCall } from "../value-objects/ToolCall.js"
 
-/**
- * Tool parameter definition for LLM.
- */
-export interface ToolParameter {
-    name: string
-    type: "string" | "number" | "boolean" | "array" | "object"
-    description: string
-    required: boolean
-    enum?: string[]
-}
-
-/**
- * Tool definition for LLM function calling.
- */
-export interface ToolDef {
-    name: string
-    description: string
-    parameters: ToolParameter[]
-}
-
 /**
  * Response from LLM.
  */
@@ -42,12 +22,16 @@ export interface LLMResponse {
 /**
  * LLM client service interface (port).
  * Abstracts the LLM provider.
+ *
+ * Tool definitions should be included in the system prompt as XML format,
+ * not passed as a separate parameter.
  */
 export interface ILLMClient {
     /**
      * Send messages to LLM and get response.
+     * Tool calls are extracted from the response content using XML parsing.
      */
-    chat(messages: ChatMessage[], tools?: ToolDef[]): Promise<LLMResponse>
+    chat(messages: ChatMessage[]): Promise<LLMResponse>
 
     /**
      * Count tokens in text.