## Summary
Adds a **Flood / Direct packet filter** dropdown to the observer
comparison page. This addresses the issue that direct packets (heard by
only one observer) skew the comparison percentages.
## Changes
- **`public/compare.js`**: Added `filterPacketsByRoute(packets, mode)`
function and a "Packet Type" dropdown (All / Flood only / Direct only)
to the comparison controls. Changing the filter re-runs the comparison
with filtered packets.
- **`test-compare-flood-filter.js`**: Unit tests for the filter
function.
## Route type mapping (from firmware)
| Route Type | Value | Filter |
|---|---|---|
| TransportFlood | 0 | Flood |
| Flood | 1 | Flood |
| Direct | 2 | Direct |
| TransportDirect | 3 | Direct |
## TDD
- Red commit: `484fa72` (test only, fails)
- Green commit: `5661f71` (implementation, tests pass)
Fixes#928
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Co-authored-by: you <you@example.com>
