feat: allow custom id factory

[Premsenareddy]

Summary

• add a public set_id_factory API for customizing AgentScope-generated entity IDs
• route message, block, event, state, task, tool response, model response, credential, storage, workspace, background task, formatter fallback, and audio block IDs through the shared factory
• keep security-sensitive gateway tokens and Redis lock tokens on raw UUID4
• add focused coverage for custom and incremental ID factories, and update formatter tests to mock the new factory

Closes #1782

Verification

• pre-commit passed for all changed files
• targeted core tests passed: 27 passed
• provider and formatter tests passed: 107 passed
• tool, storage, workspace, and TTS tests passed: 119 passed
• full local tests run: 830 passed, 19 skipped, 10 failed due local environment/pre-existing behavior: MCP server tests could not bind localhost ports under sandbox, and message-bus registry tests returned byte mappings locally.