additional scalings and new parser constructor

[jucordero]

Description

This pull request introduces new functions which can be used as temporal profiles for the different scaling models in agrifoodpy

It also registers these scaling functions with the custom !scale tag to be used in yaml configuration files.
e.g.

nodes:
  - function: agrifoodpy.utils.nodes.write_to_datablock
    name: Write a linear profile to the datablock
    params:
      key: linear_scale
      value: !scale.linear_scale [2025, 2030, 2040, 2050, 1, 1.5]

Checklist

• Follow the Contributor Guidelines
• Write unit tests
• Write documentation strings

[Copilot]

Pull request overview

This PR expands agrifoodpy’s temporal scaling utilities and integrates them into YAML pipeline configuration parsing via a custom !scale.* tag, enabling users to construct scaling xarray.DataArray profiles directly from config files.

Changes:

• Added new scaling profile functions (piecewise linear/constant/smoothstep, step, pulse, smoothstep) and refactored linear_scale to use the new piecewise implementation.
• Registered !scale.* YAML constructors in Pipeline.read() alongside existing !numpy.* / !xarray.* constructors.
• Added/expanded unit tests and YAML fixtures validating both scaling behavior and YAML parsing.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
docs/config_file.rst	Documents YAML constructors, including the new !scale.* tags and examples.
agrifoodpy/utils/scaling.py	Implements additional scaling functions and shared year-order validation.
agrifoodpy/utils/tests/test_scaling.py	Adds broader unit test coverage across the scaling utilities.
agrifoodpy/pipeline/pipeline.py	Adds !scale.* YAML multi-constructor support and scale tag resolution.
agrifoodpy/pipeline/tests/test_pipeline.py	Adds YAML parsing tests for !scale.linear / !scale.logistic (positional + kwargs) and unsupported scale tags.
agrifoodpy/pipeline/tests/data/test_config_scale_unsupported_function.yaml	YAML fixture validating unsupported !scale.* tag handling.
agrifoodpy/pipeline/tests/data/test_config_scale_logistic.yaml	YAML fixture for positional !scale.logistic.
agrifoodpy/pipeline/tests/data/test_config_scale_logistic_kwargs.yaml	YAML fixture for kwargs-based !scale.logistic.
agrifoodpy/pipeline/tests/data/test_config_scale_linear.yaml	YAML fixture for positional !scale.linear.
agrifoodpy/pipeline/tests/data/test_config_scale_linear_kwargs.yaml	YAML fixture for kwargs-based !scale.linear.

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