feat(adb): add ADB path detection service (#3)

[SamratB8]

Summary

Implements the initial ADB executable path detection service for WinDroid Runtime.

Changes

• added AdbPathResolver
• added structured AdbPathResult
• checks an optional custom ADB executable path first
• falls back to searching the current system PATH
• supports adb.exe and adb
• returns normalized absolute paths
• reports missing ADB through a structured failure result
• avoids process execution and ADB command invocation

Validation

• Debug build: 0 warnings, 0 errors
• Release build: 0 warnings, 0 errors
• git diff --check: clean
• behavioral path-resolution checks passed

No WinUI changes, process execution, bundled ADB behavior, or unrelated refactoring were included.

Closes #3.