Add tool-calling module: @Tool, ToolCallingAdvisor, returnDirect, ToolContext, and Tool Search Advisor

Every test drives the real Spring AI advisor classes (ToolCallingAdvisor,
ToolSearchToolCallingAdvisor) against a hand-written ScriptedChatModel that queues
real ChatResponse objects instead of calling a live LLM -- confirmed viable because
ChatModel has exactly one abstract method, call(Prompt) (checked with javap).

Covers:
- The plain call/execute/recall loop (WeatherTools, an ordinary @Tool method)
- @Tool(returnDirect = true) skipping the second model round trip entirely
  (ServerStatusTools)
- ToolContext: excluded from the model-facing JSON schema (verified against the
  real generated schema), still delivered to the tool from caller-supplied data
  (UserContextTools)
- A 230-tool synthetic library across six fake domains, generated via
  FunctionToolCallback.builder(...) (LargeToolLibrary)
- ToolSearchToolCallingAdvisor + RegexToolIndex: one tool ("toolSearchTool")
  offered on the first call instead of 230, with real tool-count and
  character-footprint measurements taken off the actual outgoing prompts

Findings recorded in the module's Javadoc rather than silently worked around:
- ToolCallingAdvisor only engages when the request's Prompt carries
  ToolCallingChatOptions, built from ChatModel.getOptions().mutate() (not
  getDefaultOptions(), a separate default method the request-building path never
  calls) -- confirmed by disassembling ToolCallingAdvisor.adviseCall and
  DefaultChatClientUtils
- The Tool Search Advisor's own tool is named "toolSearchTool" (camelCase), not
  "tool_search_tool" -- confirmed via @Tool(name=...) in the decompiled class
- Its session ID comes from ChatClientRequest.context() (AdvisorSpec.param), not
  from ChatClient.toolContext(Map) -- confirmed by disassembling
  ToolSearchToolCallingAdvisor.initializeSession
- RegexToolIndex matches on verb/noun substrings, not semantic relevance -- a
  real captured search for "look up an invoice" returned 5 lookup_-named tools
  across three unrelated domains alongside the one actually wanted

Co-Authored-By: Claude Sonnet 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01FtpJvZfg4nvLvtzgJTDWpB

tool-calling/output/04-tool-search-progressive-disclosure.txt

@@ -0,0 +1,11 @@
+# ToolSearchToolCallingAdvisor: one tool offered up front instead of the whole library
+
+tools registered on the ChatClient: 230
+
+tools OFFERED to the model on call 1 (before any search): 1
+  [toolSearchTool]
+
+tools OFFERED to the model on call 2 (after it searched for "look up an invoice"): 6
+  [crm_lookup_support_ticket, finance_lookup_invoice, hr_lookup_employee_record, hr_lookup_open_requisition, hr_lookup_pto_balance, toolSearchTool]
+
+final answer: Invoice INV-1001 was found in the finance system.