feat: Add SQLite database integration for aircraft history and callsign enhancement

- Implement comprehensive database package with versioned migrations
- Add skyview-data CLI tool for managing aviation reference data
- Integrate database with merger for real-time aircraft history persistence
- Support OurAirports and OpenFlights data sources (runtime loading)
- Add systemd timer for automated database updates
- Fix transaction-based bulk loading for 2400% performance improvement
- Add callsign enhancement system with airline/airport lookups
- Update Debian packaging with database directory and permissions

Database features:
- Aircraft position history with configurable retention
- External aviation data loading (airlines, airports)
- Callsign parsing and enhancement
- API client for external lookups (OpenSky, etc.)
- Privacy mode for complete offline operation

CLI commands:
- skyview-data status: Show database statistics
- skyview-data update: Load aviation reference data
- skyview-data list: Show available data sources
- skyview-data clear: Remove specific data sources

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

debian/usr/share/man/man1/skyview-data.1

@@ -0,0 +1,181 @@
+.TH skyview-data 1 "January 2025" "SkyView Database Manager"
+.SH NAME
+skyview-data \- SkyView aviation database management utility
+
+.SH SYNOPSIS
+.B skyview-data
+[\fIOPTIONS\fR] \fICOMMAND\fR [\fIARGS\fR...]
+
+.SH DESCRIPTION
+.B skyview-data
+manages the SkyView aviation database, allowing users to import airline and airport data from various external sources while maintaining license compliance.
+
+The tool automatically creates and migrates the database schema, downloads data from public and licensed sources, and provides status monitoring for the aviation database used by SkyView for callsign enhancement.
+
+.SH OPTIONS
+.TP
+.BR \-db " \fIPATH\fR"
+Database file path (auto-detected if empty)
+.TP
+.BR \-v ", " \-\-verbose
+Verbose output
+.TP
+.BR \-\-force
+Force operation without prompts
+.TP
+.BR \-\-version
+Show version information
+
+.SH COMMANDS
+.TP
+.B init
+Initialize empty database with schema
+.TP
+.B list
+List available data sources with license information
+.TP
+.B status
+Show current database status and statistics
+.TP
+.B update [\fISOURCE\fR...]
+Update data from specified sources, or all safe sources if none specified
+.TP
+.B import \fISOURCE\fR
+Import data from a specific source with license acceptance
+.TP
+.B clear \fISOURCE\fR
+Remove all data from the specified source
+.TP
+.B reset
+Clear all data and reset database (destructive)
+
+.SH DATA SOURCES
+.SS Safe Sources (Public Domain)
+These sources are automatically included in
+.B update
+operations:
+.TP
+.B ourairports
+Public domain airport database from OurAirports.com
+.TP
+.B faa-registry
+US aircraft registration database (FAA, public domain)
+
+.SS License-Required Sources
+These sources require explicit license acceptance:
+.TP
+.B openflights
+Comprehensive airline and airport database (AGPL-3.0 license)
+
+.SH EXAMPLES
+.TP
+Initialize database and import safe data:
+.EX
+skyview-data init
+skyview-data update
+.EE
+.TP
+Import OpenFlights data with license acceptance:
+.EX
+skyview-data import openflights
+.EE
+.TP
+Check database status:
+.EX
+skyview-data status
+.EE
+.TP
+Set up automatic updates via systemd timer:
+.EX
+systemctl enable skyview-database-update.timer
+systemctl start skyview-database-update.timer
+.EE
+
+.SH CRON AUTOMATION
+For automated updates, 
+.B skyview-data update
+is designed to work seamlessly with cron:
+
+.EX
+# Update weekly on Sunday at 3 AM
+0 3 * * 0 /usr/bin/skyview-data update
+.EE
+
+The command automatically:
+.RS
+.IP \(bu 2
+Creates the database if it doesn't exist
+.IP \(bu 2
+Updates only safe (public domain) sources
+.IP \(bu 2
+Provides proper exit codes for monitoring
+.IP \(bu 2
+Logs to standard output with timestamps
+.RE
+
+.SH SYSTEMD INTEGRATION
+The Debian package includes systemd timer integration:
+
+.EX
+# Enable automatic weekly updates
+systemctl enable skyview-database-update.timer
+systemctl start skyview-database-update.timer
+
+# Check timer status
+systemctl status skyview-database-update.timer
+
+# View update logs
+journalctl -u skyview-database-update.service
+.EE
+
+.SH FILES
+.TP
+.I /var/lib/skyview/skyview.db
+System-wide database location
+.TP
+.I ~/.local/share/skyview/skyview.db
+User-specific database location
+.TP
+.I /var/log/skyview/
+Log directory for database operations
+
+.SH EXIT STATUS
+.TP
+.B 0
+Success
+.TP
+.B 1
+General error or command failure
+.TP
+.B 2
+Invalid arguments or usage
+
+.SH SECURITY
+All external data downloads use HTTPS. No sensitive information is transmitted. The tool processes only publicly available aviation data.
+
+License-required sources require explicit user acceptance before import.
+
+.SH LICENSE COMPLIANCE
+.B skyview-data
+maintains strict license separation:
+.RS
+.IP \(bu 2
+SkyView binary contains no external data (MIT license maintained)
+.IP \(bu 2
+Each data source tracks its license and user acceptance
+.IP \(bu 2
+Users choose which sources to import based on license compatibility
+.IP \(bu 2
+Automatic updates only include public domain sources
+.RE
+
+.SH SEE ALSO
+.BR skyview (1),
+.BR systemctl (1),
+.BR crontab (5)
+
+.SH AUTHOR
+SkyView is developed as an open-source ADS-B aircraft tracking system.
+
+.SH REPORTING BUGS
+Report bugs and issues at the project repository.