feat: Thorough discovery mode (Axia Browse parity) + Windows 7 ComboBox fix + Telos VSet classification

Created by: ykmn

Summary

Implements Thorough discovery mode — a complete equivalent of Axia IP Audio Driver's Browse function that guarantees full channel list at the cost of longer scan time.

Changes

1. Thorough Discovery Mode (DiscoveryMode.Thorough)

• LWRP subnet sweep (TCP/93) — same as BruteForce
• Active advertisement request on port 4000 (multicast 239.192.255.3) — triggers immediate ADVT=1 "full info" announcements from all devices
• 60s passive listening on SAP (9875) + Advertisement (4001) — catches all triggered and periodic announcements
• Auto-probe for devices found only via passive (same as other modes)

2. New Files

• src/LivewireBrowser.Core/Discovery/AdvertisementRequester.cs — sends full info request packet to port 4000
• tests/LivewireBrowser.Core.Tests/AdvertisementRequesterTests.cs — basic tests
• tests/LivewireBrowser.Core.Tests/NetworkScannerTests.cs — mode logic tests

3. Device Classification

• Added Telos VSet and VSet to TelephoneHybrid category

4. Windows 7 Fix

• ComboBox dropdowns in Settings now work on Windows 7 (without Aero) by forcing open on ToggleButton click

5. Documentation

• Updated README.md and README-ru.md with Thorough mode description
• Localized EN/RU strings for new option

6. Version

• Bumped to 1.00.004 (debug increment per CLAUDE.md)
• Updated HISTORY.md

Testing

• All 109 tests pass
• Build succeeds with 0 warnings