Add radar scope, splash screen, Star Wars easter egg, and harden TUI

New features:
- P1 green phosphor radar scope widget on Track screen with LUT-optimized rendering
- Splash screen with pre-baked ANSI half-block art from 16colo.rs/Mistigris
- Star Wars ASCII animation via telnet (ctrl+w) with IPv6 happy eyeballs and offline fallback
- Dark Side / New Hope toast notifications on theme toggle
- Kitty terminal detection with cat emoji on splash

Robustness (from Apollo code review):
- Circuit breaker in track loop after 10 consecutive errors
- Input validation for frequency, symbol rate, step size across scan/spectrum/track
- Consolidated sys.path manipulation into __init__.py
- Radar scope pre-computes dist/angle LUT per pixel on resize

Cleanup:
- Removed unused imports across lband, monitor, scan, signal_gauge
- Moved Pillow/textual-image to optional dev deps (splash uses pre-baked ANSI)
- Added 41-test pytest suite covering telnet IAC parsing, radar geometry, splash assets

tui/src/skywalker_tui/assets/splash/CREDITS.md

@@ -0,0 +1,13 @@
+# Splash Art Credits
+
+
+All artwork sourced from [16colo.rs](https://16colo.rs) /
+[Mistigris](https://mistigris.com) art packs.
+
+| File | Artist | Title | Pack |
+|------|--------|-------|------|
+| `seti-satellite.png` | Illarterate | S.E.T.I. Satellite | [mist0717](https://16colo.rs/pack/mist0717) |
+| `dialtone.jpg` | 192.168.10.13 | Dialtone | [mist1119](https://16colo.rs/pack/mist1119) |
+| `so-far-away.gif` | Blippypixel | So Far Away | [mist0523](https://16colo.rs/pack/mist0523) |
+| `prodigy-out-of-space.jpg` | Jellica Jake | Prodigy / Out of Space | [mist0121](https://16colo.rs/pack/mist0121) |
+| `space-docker.gif` | Blippypixel | Space Docker | [mist1120](https://16colo.rs/pack/mist1120) |