Feature/v3/invest multi period

[FBumann]

Description

Add advanced Multi Period Investment modeling to flixopt

Type of Change

• Bug fix
• New feature
• Documentation update
• Code refactoring

Related Issues

Closes #(issue number)

Testing

• I have tested my changes
• Existing tests still pass

Checklist

• My code follows the project style
• I have updated documentation if needed
• I have added tests for new functionality (if applicable)

Summary by CodeRabbit

• New Features
  • Added time-aware investments via InvestTimingParameters and InvestmentTimingModel, including year_of_investment support and lifecycle constraints.
  • FlowSystem now supports years_of_last_year, years_per_year, and year_of_investment, improving year-based selections and effects alignment.
  • transform_data methods accept an optional name_prefix across interfaces, elements, and effects.
  • Enhanced modeling primitives: duration tracking now parameterized; added continuous transition bounds and binary-linked level-change utilities.
• Bug Fixes
  • Investment result aggregation now recognizes timing-based investment models.
• Tests
  • New tests and helpers for year-aware investment timing and annualized effects.

[FBumann]

Outdated. Continued in #452