Update nanny callers: Task NamedTuple + migrate inputgen/validator/aggregator

[Michael628]

Target branch: feature/issue-1-registry-refactor (based off develop)
All PRs for this work should target this branch, not main.

Parent PRD

#1

What to build

Change create_task in nanny/core.py to return a Task NamedTuple holding both the handler and the built config. Update all callers (inputgen.py, validator.py, aggregator.py) to pass config explicitly to handler domain functions. Remove dynamic format_string registration from nanny/core.py — callers use config.format_string() directly. Remove handler.config mutation.

Acceptance criteria

• Task NamedTuple with handler: TaskHandler and config: ConfigBase fields
• create_task returns Task instead of a handler with config baked in
• inputgen.py passes config explicitly to handler.build_input_params(config) and uses config.format_string() / config.runid directly
• validator.py passes config explicitly to handler.create_outfile_catalog(config)
• aggregator.py passes config explicitly to handler.build_aggregator_params(config, average)
• Dynamic format_string registration in nanny/core.py removed
• All existing nanny tests continue to pass

Blocked by

• Blocked by Rewrite registration functions + migrate all task registrations #5 (registration migration)

User stories addressed

• User story 6
• User story 15