Add Analytics API service and Drush commands for AI integration

[jjroelofs]

Summary

Adds a service-based analytics API (rl.analyzer) that enables both Drush commands and other Drupal modules to access experiment performance data, insights, and recommendations.

Architecture:

RlAnalyzerInterface (contract)
       ↓
  RlAnalyzer (service - all business logic)
       ↓
  ┌────┴────┐
Drush     Other modules
Commands  (via dependency injection)

Features

Service API (rl.analyzer)

• listExperiments() - All experiments with summary stats
• getStatus($experimentId) - Detailed status with confidence levels
• getPerformance($experimentId, $limit) - Arm data with human-readable labels
• getTrends($experimentId, $period, $periods) - Historical analysis
• export($experimentId, $includeSnapshots) - Full data export

Drush Commands

• rl:list - List all experiments
• rl:status <experiment> - Experiment status
• rl:performance <experiment> - Arm performance
• rl:trends <experiment> - Historical trends
• rl:analyze <experiment> - Full analysis with recommendations
• rl:export <experiment> - Complete data export

Key Capabilities

• Human-readable labels - Entity IDs resolved to titles (node titles, etc.)
• Pre-computed insights - vs_average, confidence, trend direction
• JSON/YAML output - Structured data for AI consumption
• Actionable recommendations - "Ready to conclude", "Continue monitoring", etc.

Usage Examples

# List all experiments
drush rl:list --format=json

# Get detailed status
drush rl:status ab_test_button_color --format=yaml

# Get top performers with resolved labels
drush rl:performance ai_sorting-help_center_categories-block_1 --limit=10

# Full AI-friendly analysis
drush rl:analyze my_experiment --format=json

// Other modules can inject the service
$analyzer = \Drupal::service('rl.analyzer');
$performance = $analyzer->getPerformance('my_experiment', limit: 10);

Test Plan

• Test rl:list command with table and JSON output
• Test rl:status with YAML output
• Test rl:performance with entity label resolution
• Test rl:trends with historical data
• Test rl:analyze with recommendations
• Test rl:export with and without snapshots
• Verify browser charts still work

[jjroelofs]

Duplicate of #26 (base branch was changed to 1.x)