feat: implement storybook DSL with template composition and validation

Add complete domain-specific language for authoring narrative content for
agent simulations.

Features:
- Complete parser using LALRPOP + logos lexer
- Template composition (includes + multiple inheritance)
- Strict mode validation for templates
- Reserved keyword protection
- Semantic validators (trait ranges, schedule overlaps, life arcs, behaviors)
- Name resolution and cross-reference tracking
- CLI tool (validate, inspect, query commands)
- Query API with filtering
- 260 comprehensive tests (unit, integration, property-based)

Implementation phases:
- Phase 1 (Parser): Complete
- Phase 2 (Resolution + Validation): Complete
- Phase 3 (Public API + CLI): Complete

BREAKING CHANGE: Initial implementation

tests/compiler_errors/README.md

@@ -0,0 +1,55 @@
+# Compiler Error Examples
+
+This directory contains example `.sb` files that demonstrate each type of error
+the Storybook compiler can detect. Each file is intentionally incorrect to showcase
+the error messages and helpful hints.
+
+## How to Run
+
+To see all error messages, validate each file individually:
+
+```bash
+# From the storybook root directory
+cargo build --release
+
+# Run each file to see its error
+./target/release/sb validate tests/compiler_errors/01_unexpected_token.sb
+./target/release/sb validate tests/compiler_errors/02_unexpected_eof.sb
+./target/release/sb validate tests/compiler_errors/03_invalid_token.sb
+# ... etc
+```
+
+Or use this script to show all errors:
+
+```bash
+#!/bin/bash
+for file in tests/compiler_errors/*.sb; do
+    echo "═══════════════════════════════════════════════════════════"
+    echo "File: $(basename $file)"
+    echo "═══════════════════════════════════════════════════════════"
+    cargo run --bin sb -- validate "$file" 2>&1 || true
+    echo ""
+done
+```
+
+## Error Categories
+
+### Parse Errors (Syntax)
+- `01_unexpected_token.sb` - Missing colon after field name
+- `02_unexpected_eof.sb` - Incomplete declaration
+- `03_invalid_token.sb` - Invalid character in syntax
+- `04_unclosed_prose.sb` - Prose block missing closing `---`
+
+### Validation Errors (Semantics)
+- `05_trait_out_of_range.sb` - Trait value outside 0.0-1.0 range
+- `06_age_out_of_range.sb` - Age value outside 0-150 range
+- `07_unknown_life_arc_state.sb` - Transition to undefined state
+- `08_schedule_overlap.sb` - Schedule blocks overlap in time
+- `09_unknown_behavior_action.sb` - Undefined behavior tree action
+- `10_duplicate_field.sb` - Same field name used twice
+- `11_relationship_bond_out_of_range.sb` - Bond value outside 0.0-1.0 range
+
+Each error includes:
+- ✓ Clear error message explaining what went wrong
+- ✓ Helpful hint on how to fix it
+- ✓ Context-specific suggestions