perf: add 200MB image disk cache, RAM memory cache, and network connection pooling

[neerajlovecyber]

Summary

Optimizes image caching, memory utilization, and network concurrency across NuvioDesktop:

• Coil 3 Persistent Disk & RAM Cache: Added 200MB persistent disk cache in OS-standard cache directories (%LOCALAPPDATA%/Nuvio/image_cache\ on Windows, ~/Library/Caches/com.nuvio.app/image_cache\ on macOS, ~/.cache/nuvio/image_cache\ on Linux) and configured a 25% JVM heap \MemoryCache.
• Addon & Trailer Connection Pooling: Configured OkHttp \ConnectionPool(16, 5 min)\ and high-concurrency dispatchers (\maxRequests = 64, \maxRequestsPerHost = 16) for addon scraping and trailer extraction.
• DNS Sorter: Added \DesktopIPv4FirstDns\ to trailer extraction clients.

PR type

• Small maintenance only, with no UI or behavior change

Why

• Missing Coil persistent disk cache caused NuvioDesktop to re-download all posters, banners, and backdrops over the network on every app launch.
• Default connection limits caused TLS connection overhead and queuing during multi-addon scraping.

Desktop scope

This change is 100% desktop-specific (\desktopMain):

• Windows (%LOCALAPPDATA%), macOS (~/Library/Caches), Linux (~/.cache).
• No \commonMain\ shared files were modified.

Issue or approval

No linked issue: performance and caching maintenance for desktop.

UI / behavior impact

• No UI change
• No behavior change

Policy check

• I have read and understood \CONTRIBUTING.md.
• This PR is small, focused, and limited to one problem.
• This PR is scoped to the desktop app, desktop packaging, desktop documentation, or shared code required for desktop behavior.
• This PR is not cosmetic-only.
• Any UI change fixes a linked glitch/bug and includes visual proof, or this PR has no UI change.
• Any behavior change fixes a linked bug/regression or has explicit approval, or this PR has no behavior change.
• This PR does not bundle unrelated refactors, cleanups, formatting, or drive-by changes.
• This PR does not add dependencies, architecture changes, migrations, or product-direction changes without explicit approval.
• I listed the testing performed below.

Scope boundaries

• Strictly touches desktop-specific caching and network infrastructure (\desktopMain).
• No UI components, navigation, or database schemas were touched.

Testing

• Desktop OS: Windows 11 x64.
• Commands: ./gradlew :composeApp:compileKotlinDesktop.
• Manual Verification:
  • Validated local cache creation in %LOCALAPPDATA%/Nuvio/image_cache.
  • Verified instant poster loading from disk on repeated launches.
  • Verified multi-addon scraping over pooled \desktopHttpClient\ sockets.

Screenshots / Video

Not a UI change

Breaking changes

None.

Linked issues

No linked issue: desktop performance and caching maintenance.

[neerajlovecyber]

Hi @KhooLy , I forgot to mention this changes are just alining desktop behaviour with tv mostly 1:1