Add comprehensive PuTTY session import feature

[steffen-heil-secforge]

Summary

Implements full import of PuTTY sessions from Windows registry export files, including connection settings and port forwards. Users can import multiple sessions at once through an interactive dialog with selective import and bind address configuration.

Note: This PR is based on #5 (wifi-hotspot-forwarding branch) and should be merged after that PR.

Features

PuTTY Registry Parsing

• Parse PuTTY registry export files (.reg format)
• Extract session configurations: hostname, port, protocol (ssh/telnet/local/serial), username, compression
• Parse all port forward types:
  • Local forwards (-L): L<sourceport>=<destaddr>:<destport>
  • Remote forwards (-R): R<sourceport>=<destaddr>:<destport>
  • Dynamic SOCKS (-D): D<sourceport>
• Handle complex syntax: IPv6 addresses, bind addresses, custom ports
• Validate port numbers and addresses
• Convert PuTTY constants to ConnectBot database constants
• Truncate at 100 sessions with user notification

Interactive Import Dialog

• Multi-select session list with checkboxes
• Session details displayed: username@hostname:port
• Indicators for existing hosts (shows which will be updated vs. new)
• Filtered list excludes identical sessions already in database
• Select all / deselect all buttons
• Sorted alphabetically by session name
• Bind address configuration for imported port forwards:
  • localhost (default, matches PuTTY semantics)
  • All interfaces (0.0.0.0)
  • WiFi hotspot (access_point)
• Security warnings for network-exposed bind options

Smart Merge Behavior

• When session name matches existing host:
  • Updates only PuTTY-related fields: protocol, hostname, port, username, compression
  • Preserves all ConnectBot settings: colors, key usage, font size, stay-connected, quick-disconnect, auth agent, post-login, session flags, encoding
• Port forwards are fully replaced (old deleted, new imported) to prevent duplicates on re-import
• Sessions identical to existing hosts are filtered out

Background Import

• AsyncTask with progress dialog
• Import results: success count, skipped count, errors
• Toast notifications for all result states:
  • Full success: "Imported N sessions"
  • Partial success: "Imported N sessions (M skipped)"
  • Error: Specific error message
• Automatic host list refresh after import

Lifecycle Handling

• Graceful handling of fragment recreation (configuration changes)
• Dialog dismisses on recreation rather than attempting to serialize non-serializable data
• User can simply re-trigger import if needed

UI Integration

• "Import from PuTTY" menu action in HostListActivity
• File picker for selecting .reg files
• Custom layouts:
  • dia_putty_import.xml: Main import dialog
  • item_putty_session.xml: Session list item
• Comprehensive string resources for all UI text

Parser Capabilities

Supported PuTTY Fields

• HostName: Target hostname/IP
• PortNumber: SSH/telnet port
• Protocol: ssh, telnet, local, serial
• UserName: Login username
• Compression: Enable/disable compression
• PortForwardingX: All port forward definitions

Port Forward Parsing

• Handles all formats:
  • L8080=localhost:80 (local forward)
  • R2222=192.168.1.100:22 (remote forward)
  • D1080 (dynamic SOCKS proxy)
  • L6[::1]:8080=[2001:db8::1]:80 (IPv6 with bind address)
• Validates port ranges (1-65535)
• Extracts bind addresses when specified
• Provides informative warnings for malformed entries

Testing

Comprehensive unit tests in PuttyRegistryParserTest:

• Local, remote, and dynamic port forwards
• IPv6 address handling
• Custom port numbers
• Bind address extraction
• Malformed input handling
• Session truncation behavior
• Warning collection

[steffen-heil-secforge]

Superseded by #9 (ported to new Kotlin/Compose/Room architecture)