fix: enable Layer 3 sync by adding root events to pending queue

When root events (issues/patches) are received via self-subscription,
handle_root_event() was only updating the repo_sync_index directly.
This caused process_batch() to early-return when pending.is_empty(),
so Layer 3 filters for comments/replies were never created.

The fix adds root events to both:
1. repo_sync_index (for immediate availability)
2. pending queue (to trigger Layer 3 filter creation in next batch)

Critical: The pending entry must include relays from repo_sync_index
so derive_relay_targets() knows where to send Layer 3 subscriptions.

The Layer 3 test now verifies that events sent BEFORE the subscription
is established are still synced - proving subscriptions without 'since'
correctly fetch historical events.

Enabled 4 previously ignored Layer 3 tests:
- test_live_sync_layer3_events
- test_layer3_sync_with_lowercase_e_tag
- test_layer3_sync_with_uppercase_e_tag
- test_layer3_sync_with_q_tag

0 files changed, 0 insertions, 0 deletions