Add spec for CanonicalMetadataSync service and fix multiple variable reference bugs

[Copilot]

This PR adds comprehensive test coverage for the CanonicalMetadataSync service and fixes critical bugs that would prevent the service from functioning correctly in production.

Fixed Bugs

Bug 1: Variable reference error that would cause immediate failure:

# Before (broken):
liq = LiquidsoapRequests.new r.id

# After (fixed):
liq = LiquidsoapRequests.new radio.id

Bug 2: Incorrect radio selection in multi-radio environments:

# Before (broken):
current_show = Radio.first.current_scheduled_show

# After (fixed): 
current_show = radio.current_scheduled_show

The first bug would cause a NameError since r was undefined. The second bug would cause incorrect behavior by always using the first radio's scheduled show instead of the specific radio being processed, leading to wrong metadata in multi-radio setups.

Test Coverage

Added spec/services/canonical_metadata_sync_spec.rb with comprehensive test coverage:

• Live DJ source testing: Verifies metadata sync when live DJs are broadcasting
• Scheduled shows source testing: Tests metadata extraction from currently running shows
• Backup playlist source testing: Validates fallback to archive metadata
• Edge case handling: Tests whitespace trimming, missing archive data, and multi-radio scenarios
• Redis storage verification: Ensures metadata is properly stored with correct keys

The spec includes 8 test cases covering all audio source types (live_dj, scheduled_shows, backup_playlist, unknown) and various edge cases to ensure robust canonical metadata synchronization across all streaming scenarios.

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[mcfiredrill]

@copilot rebase or merge against main

spec is also failing currently

[Copilot]

@copilot rebase or merge against main

spec is also failing currently

✅ Rebase completed successfully against main branch. Also fixed an additional bug in the service where Radio.first.current_scheduled_show was incorrectly used instead of radio.current_scheduled_show, which would cause issues in multi-radio environments. Updated the spec mocks accordingly. Changes are in commit a1b8ebde.