Add CSV and SQLite reporters

[Zious11]

Summary

Add CSV and SQLite export formats alongside the existing terminal and JSON reporters.

Requirements

CSV Reporter

• Implement Reporter trait in src/reporter/csv.rs
• Export findings as CSV rows (one finding per row)
• Export summary stats as a separate CSV section or file
• Use the csv crate (already in dependencies)

SQLite Reporter

• Implement Reporter trait in src/reporter/sqlite.rs
• Create tables: findings, summary, hosts, protocols, services
• Use rusqlite crate (needs to be added to Cargo.toml)
• Support --sqlite <path> CLI flag

Acceptance Criteria

• CsvReporter implements Reporter, outputs valid CSV
• SqliteReporter creates a queryable .db file
• Wire up --output-format csv and --sqlite CLI flags
• Tests for both formats