Make tool factories and PluginTools accept a live config callable

[yzx9]

Config can now be passed as a zero-arg callable (() -> Config) in addition to a static instance. resolve_config() dynamically detects and resolves it at execution time, so tools observe update_config() changes without being rebuilt.

• core.config: add ConfigProvider, ConfigLike (Config | ConfigProvider, PEP 604), and resolve_config(); exported via all.
• research_tools: the four makeXXX factories resolve cfg lazily inside each closure; drop the dead 'cfg or load_config()' fallback.
• workflow.batch_qc: make_batch_precheck now uses ConfigLike/resolve_config (previously an inline duplicate resolver); LeaderAgent passes its ConfigLike provider directly instead of a lambda that would yield a nested callable.
• agent_loader: widen cfg to ConfigLike and pass it straight through (no resolve).
• tools.PluginTools: accept ConfigLike, resolve via a 'cfg' property, and snapshot config once per method to avoid mid-method inconsistency.
• leader_multiagent: LeaderDriven.get_config() returns the current live config; pass it as the provider to load_agent_configs and LeaderAgent.
• tests: factory liveness test, PluginTools.cfg resolution test, static-config passthrough tests.

Backward compatible: existing callers passing a static Config keep working. Known limitation: update_config currently only mutates LLM fields, so the makeXXX tools stay inert until update_config is widened (follow-up).