feat: v3.1.0 — Major codebase overhaul, fix f-string SyntaxError #16, enhanced LevelDB disk cache & improved resume feature

[th3sanjai]

🚀 v3.1.0 — Major Codebase Overhaul

This release brings a full codebase improvement to SubProber with critical bug fixes, performance enhancements, and a more robust resuming system.

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🐛 Bug Fixes

Fixes #16 — SyntaxError: f-string: expecting '}'

• Identified and resolved malformed f-string expressions causing SyntaxError on certain Python versions
• Refactored all affected f-strings ensuring full compatibility across Python 3.8+

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⚡ Enhancements

🗄️ Enhanced Disk Cache with pyleveldb

• Completely replaced the old caching mechanism with pyleveldb (LevelDB) for persistent, high-performance disk caching
• LevelDB's key-value storage delivers significantly faster read/write speeds for large-scale subdomain probing
• Cache persists across process restarts — no more redundant HTTP requests on repeated runs
• Massive performance boost when probing large subdomain lists

🔁 Improved Resume Feature

• Fully overhauled resume mechanism to accurately track and persist probing progress
• SubProber now seamlessly resumes from the exact point of interruption (Ctrl+C, crash, or timeout)
• Resume state is tightly integrated with the LevelDB cache for full consistency
• Eliminates re-probing of already completed subdomains — saves significant time on large targets

🛠️ Full Codebase Overhaul

• Refactored and cleaned up the entire codebase for better readability and maintainability
• Improved internal architecture for better modularity and extensibility
• Optimized async handling for faster concurrent probing
• Better error handling and edge case management throughout
• Improved output formatting and logging consistency

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📦 Dependency Updates

• Added pyleveldb as a new dependency for disk caching

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✅ Testing

• Tested on Python 3.8, 3.10, 3.12
• Verified LevelDB cache persistence across interrupted and resumed sessions
• Confirmed f-string SyntaxError fix resolves issue SyntaxError: f-string: expecting '}' #16
• Large-scale subdomain list probing verified with resume accuracy

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Closes #16