feat(tools_api): add upsert support to create_tool_from_schema

[konradszymanski]

create_tool_from_schema now updates existing tools instead of failing on unique constraint.

Problem:
When calling create_tool_from_schema with an existing tool code, it failed with:
ORA-00001: unique constraint (KS.UC_AI_TOOLS_UK) violated on table KS.UC_AI_TOOLS columns (CODE)

Solution:

Check if tool with same code exists before insert
If exists: update the tool record, delete and recreate parameters and tags
If not exists: create new tool as before
Use Case:
Users may call uc_ai_tools_api.create_tool_from_schema multiple times to quickly update parameter values, tool instructions, or other tool configuration without needing to manually delete the tool first.

Changes:

uc_ai_tools_api.pkb: Added upsert logic to create_tool_from_schema
uc_ai_tools_api.pks: Updated documentation to reflect new behavior