feat: Add Designer Feedback Loop and Tooling (M11.6)

[Copilot]

Build designer-facing tools for balance iteration without requiring code changes. Provides CLI workflows, YAML config overlays, and HTML report generation.

Changes

New Package: src/gengine/balance_studio/

• overlays.py - YAML overlay system for testing config changes against base configs
• workflows.py - Sweep, compare, and tuning test workflow implementations
• report_viewer.py - Interactive HTML report generation with filtering/sorting
• cli.py - Entry point for echoes-balance-studio command

CLI Tool: scripts/echoes_balance_studio.py

Four guided workflows:

1. Run exploratory sweep
2. Compare two configs
3. Test tuning change
4. View historical reports

echoes-balance-studio sweep --strategies balanced,aggressive --seeds 5
echoes-balance-studio compare config_a.yml config_b.yml
echoes-balance-studio test-tuning --overlay overlays/aggressive_economy.yml
echoes-balance-studio view-reports --html output.html

Example Overlays: content/config/overlays/

• aggressive_economy.yml - Economy tuning example
• fast_pacing.yml - Narrative pacing example

Documentation: docs/gengine/designer_feedback_tooling.md

• Diagnosing dominant strategies
• Iterating on action costs
• Testing narrative pacing changes
• Case study: Balancing the Industrial Tier faction

Tests

30 tests covering CLI commands, overlay loading, and report generation (tests/scripts/test_echoes_balance_studio.py)

Original prompt

"Designer Feedback Loop and Tooling (Issue #70)" to gamedev agent

Created from Copilot CLI via the copilot delegate command.

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