feat(discovery): Cross-Platform Runtime Discovery, Dual-OS CI & Installer Automation (v3.8.0)

[spelech]

Summary of Changes

• FFmpeg Discovery with Hardware Encoder Telemetry: Discovers local and PATH FFmpeg binaries and queries supported hardware encoders (NVENC/CUDA, Intel QSV, VAAPI, AMD AMF).
• Python Audio TTS Environment Discovery: Discovers Python environments (virtualenvs, PATH, portable) and checks for required audio synthesis packages (kokoro-onnx, soundfile, fastapi, uvicorn, openai).
• Cross-Platform Linux Paths & Shell Runners: Added Linux discovery roots (/opt, /srv, /data, /mnt, etc.) and Linux runners (webui.sh, webui-user.sh, run.sh, start.sh) for ComfyUI, Forge, and Audio engines.
• Dual-OS CI Matrix: GitHub Actions ci.yml now tests across [windows-latest, ubuntu-latest] with Playwright browser dependencies.
• Installer Automation:
  • scripts/install.ps1: Added -Firewall switch and Windows Defender Firewall inbound rule creation for port 5246, WinGet FFmpeg prompt/installation, Python audio packages installation, and network connection URL summary.
  • scripts/installer.iss: Added firewall task to register port 5246 firewall rule on setup and clean up on uninstall.
  • scripts/install_linux.sh: Added package manager FFmpeg prerequisite installation, UFW/firewalld port 5246 opening, Python audio package installation, and systemd service generation.
• Version Bump: Bumped project version to 3.8.0 across project files, Inno Setup, README, and docs.