perf: ultra-low-impact v1.5.0 runtime

[Zudin987]

Goal

Minimize BlueMeter Lite's impact on BPSR FPS, thermals and battery without removing the core Damage, Healing, Tanking, overlay, encounter history or reset features.

Runtime changes

• selector-driven TCP/UDP VPN forwarding; removes the 1 ms polling loop
• bounded TUN queue with backpressure, capped pools and UDP idle expiry
• full UDP four-tuple session keys
• lower-copy TCP segmentation and retransmission/out-of-order guards
• direct native EventChannel bridge instead of Android packet broadcasts
• reusable offset-based Dart packet reassembly and zero-copy views
• bounded unknown-combat staging so NPCs do not become player DPS/DB candidates
• coalesced player metadata UPSERTs and daily DB/history cleanup
• event-driven overlay updates with one throttle instead of two stacked timers
• less hot-path wall-clock and specialization parsing work
• unused Lite runtime dependencies/assets removed

Regression protection

• 10,000-packet replay test
• fragmentation/reset reassembly tests
• NPC/player combat staging tests
• static CI guards against the old polling/copy/broadcast/timer/DB patterns
• generated-source analysis + Flutter tests + release APK build

Release

Bumps to 1.5.0+25. After merge, the release workflow is configured to build signed split APKs, verify signatures and publish v1.5.0 as latest.