feat: add PAC/Stanley tag type support

[matteoscrugli]

Summary

Adds GUI support for the PAC/Stanley LF tag type. The firmware has full PAC support (scan, emulate, T55xx write) but the GUI has never exposed it.

Motivation

PAC/Stanley is a mainstream LF credential already implemented in the Chameleon Ultra firmware: TAG_TYPE_PAC = 150 plus four DATA_CMD_PAC_* commands. Without GUI wiring, users must drop to the Python CLI to provision PAC slots.

Changes

helpers/definitions.dart

• Add TagType.pac(150)
• Add ChameleonCommand.scanPacTag(3014), writePacToT5577(3015), setPacEmulatorID(5006), getPacEmulatorID(5007)
• New PacCard extends LFCard (modeled on VikingCard)

bridge/chameleon.dart

• readPac, setPacEmulatorID, writePacToT55XX, getPacEmulatorID

helpers/general.dart

• Display name "PAC/Stanley" (matches firmware CLI), add to LF tag type list, getLFCardFromUID factory, uidSizeForLfTag = 8 bytes

helpers/write.dart, helpers/t55xx/write/base.dart

• Route PAC through the existing T55xx write helper with read-back verification

gui/page/slot_manager.dart, gui/menu/dialogs/slot/edit.dart, gui/menu/dialogs/slot/export.dart, gui/page/read_card.dart

• Branches to save a PAC CardSave into a slot, load/save the emulator ID in the slot edit dialog, export the slot back to a CardSave, and include PAC in the LF reader scan chain

gui/page/home.dart

• Bump the firmware capability gate from setVikingEmulatorID to setPacEmulatorID

Testing

• flutter analyze lib/ clean (no new issues)
• flutter build macos --debug succeeds
• No regressions on existing LF tag types (EM410x / HIDProx / Viking)

Pattern

The implementation follows the Viking integration 1:1 (simplest existing LF tag with raw-hex UID). Same file touches, same else-if chain placement.

[GameTec-live]

Nothing jumps out to me. Dont have a PAC card tho, so someone please test.

[matteoscrugli]

Consolidated into #844 as you suggested, that PR bundles PAC and IDTECK into a single change set, so there are no merge conflicts between parallel branches anymore. Closing this in favour of the unified PR. Thanks for the heads-up!