Smart Table Reset & Navigation Bug Fixes (v2.24)

[w3spi5]

Summary

This PR introduces Smart Table Reset to automatically handle "Table already exists" errors, fixes critical navigation bugs, and improves header styling.

Changes

✨ New Features

• Smart Table Reset: Automatically DROP tables before import
  • Pre-scans SQL files for CREATE TABLE statements (.sql, .gz, .bz2)
  • Prevents "Table already exists" errors on re-imports
  • Secure table name validation with regex + backtick quoting
  • Graceful degradation: import continues if reset fails

🐛 Bug Fixes

• Session cleanup after SSE error: Fixed stale session data causing silent failures on retry
• Navigation links: Fixed broken "Back to Home" links in various installation paths
  • error.php: ../ → $scriptUri
  • import.php: / → $scriptUri (was going to server root!)
  • layout.php / layout_phar.php: ./ → $scriptUri

🎨 UI Improvements

• Header gradients: Theme-aware pastel gradients for light/dark modes

Test Plan

• SmartTableResetTest.php - 7 tests (table extraction, gzip, deduplication, security)
• Manual test: re-import same file without manual DROP
• Manual test: navigation from subdirectory installation