refactor(config): split ProtostarConfig into UserConfig and TemplateBlueprint

[JacksonFergusonDev]

Description

This PR resolves the "God Object" anti-pattern in ProtostarConfig by separating global user configuration from template-specific scaffolding state.

Architecture Changes

• Split Configuration: Renamed ProtostarConfig to UserConfig to represent global, persistent settings (e.g., ide, author_name, and tooling toggles).
• Extracted TemplateBlueprint: Encapsulates ephemeral, target-specific state (e.g., active_presets, files, dev_dependencies, and template variables).

Engine Updates

• Orchestrator & CLI Refactored: Updated cli.py, orchestrator.py, and wizard.py to independently ingest and handle both UserConfig and TemplateBlueprint configurations across the scaffolding lifecycle.
• Dynamic Variable Resolution: Intercepts missing template variables during blueprint loading to seamlessly trigger the interactive TUI wizard when necessary.
• Preset Isolation: Decoupled the PresetModule interface in base.py from attempting to read a global presets mapping that shouldn't exist, preventing attribute leakage.

Testing & Validation

• Fully updated tests/ (specifically test_config.py, test_cli.py, test_orchestrator.py, and test_presets.py).
• Improved isolated file I/O mocking inside with an autouse fixture.
• just test-unit completely passes, along with mypy and ruff static analysis checks.