feat: Add Designer Feedback Loop and Tooling (Issue #70, Task 11.6.1)

- Add echoes-balance-studio CLI tool with 7 guided workflows
- Implement config overlay system for testing tuning changes
- Create interactive HTML report viewer with filtering/sorting
- Add designer-focused documentation and case studies
- Include 28 tests covering CLI, overlays, and reports

Co-authored-by: SorraTheOrc <250240+SorraTheOrc@users.noreply.github.com>

Author: Copilot

content/config/overlays/example_tuning.yml

@@ -0,0 +1,46 @@
+# Example Tuning Overlay for Echoes of Emergence
+# ================================================
+#
+# This file demonstrates how to create configuration overlays for balance testing.
+# Overlays merge with the base simulation.yml, allowing you to test parameter
+# changes without modifying the base configuration.
+#
+# Usage:
+#   echoes-balance-studio test-tuning --overlay content/config/overlays/example_tuning.yml
+#
+# Structure:
+#   Only include the settings you want to change. Missing settings will use
+#   base configuration values. Nested sections are deep-merged.
+
+# Metadata (optional) - helps document what this overlay is testing
+_meta:
+  name: "Example Tuning Overlay"
+  description: "Demonstrates adjusting economy and environment parameters"
+  author: "Balance Team"
+  created: "2025-12-05"
+  hypothesis: "Increasing regen_scale should improve stability without making the game too easy"
+
+# Economy adjustments
+# Hypothesis: Slightly faster resource regeneration helps new players
+# without trivializing resource management
+economy:
+  # Increase base regeneration by 25% (0.8 -> 1.0)
+  regen_scale: 1.0
+  # Slightly reduce the threshold for shortages to trigger earlier warnings
+  shortage_threshold: 0.25
+  # Allow prices to fluctuate more for interesting market dynamics
+  price_max_boost: 0.6
+
+# Environment adjustments
+# Hypothesis: Softer scarcity pressure gives players more recovery time
+environment:
+  # Reduce how much scarcity affects unrest
+  scarcity_unrest_weight: 0.00003
+  # Allow biodiversity to recover faster
+  biodiversity_recovery_rate: 0.05
+
+# Director adjustments (optional)
+# Hypothesis: Longer quiet periods between story seeds reduces overwhelm
+# director:
+#   global_quiet_ticks: 6
+#   seed_quiet_ticks: 8

docs/gengine/ai_tournament_and_balance_analysis.md

@@ -251,9 +251,32 @@ A nightly CI workflow automatically runs tournaments and batch sweeps, archiving
 - Use `--verbose` during development to monitor sweep progress.
 - Use reproducible seeds for regression testing.
 
+## Designer Feedback Loop and Tooling
+
+For designer-friendly workflows that make balance iteration accessible without deep engineering knowledge, see the [Designer Balance Guide](./designer_balance_guide.md). This guide covers:
+
+- Running exploratory parameter sweeps with `echoes-balance-studio`
+- Creating and testing config overlays
+- Diagnosing dominant strategies
+- Iterating on action costs and narrative pacing
+- Example workflows with case studies
+
+Quick start:
+```bash
+# Run the balance studio
+uv run echoes-balance-studio sweep --strategies balanced aggressive --ticks 50
+
+# Test a tuning change
+uv run echoes-balance-studio test-tuning --overlay content/config/overlays/example_tuning.yml
+
+# View historical reports
+uv run echoes-balance-studio history --days 30
+```
+
 ## See Also
+- [Designer Balance Guide](./designer_balance_guide.md) - Designer-focused balance workflows
 - [How to Play Echoes](./how_to_play_echoes.md)
 - [Implementation Plan](../simul/emergent_story_game_implementation_plan.md)
 - [README](../../README.md)
- - [Testing Guide](./testing_guide.md)
- - [Content Designer Workflow](./content_designer_workflow.md)
+- [Testing Guide](./testing_guide.md)
+- [Content Designer Workflow](./content_designer_workflow.md)