Task: Make the installer register the handler

TASK-DESCRIPTION

Modify: scripts/program-install.sh
Create: tests/91-install-handler.sh
Modify: Makefile
Modify: README.md
Modify: TODO.md
Modify: prompts/features/05-pkpass-handler.md
Modify: prompts/tasks/00-tasks.md

The installer implements the requirement in prompts/features/05-pkpass-handler.md PKPASS-HANDLER-R021: installing the tools also registers the handler, so a pass opens without a second command.

Registering must stay reversible and skippable: PKPASS_INTEGRATION_NO_HANDLER=1 installs the programs and registers nothing, and pkpass-integrate handler uninstall reverses a registration at any time. The registration runs the freshly installed program, so the desktop entry points into the installation prefix rather than at the build tree. A failure to register is reported, leaves the installed programs in place, and makes the command exit nonzero, so a scripted install cannot believe it finished when the association is missing.

TASK-OUTPUT

Produce these complete files in this order, then the VERIFICATION: line: 1. scripts/program-install.sh 2. tests/91-install-handler.sh 3. Makefile 4. README.md 5. TODO.md 6. prompts/features/05-pkpass-handler.md 7. prompts/tasks/00-tasks.md

TASK-CONTEXT

program-install.sh is what make install runs; scripts/install.sh, the release installer, stays a separate entry point that a release tarball drives, and it prints the integration step rather than performing it. The installer is unattended, so the choice comes from an environment variable and the failure is closed (prompts/03-conventions.md section 7.1). See documents/09-mime-type-association.md for what the registration writes.

The test must point HOME and every XDG_ path at a throwaway directory, so it never registers the handler on the machine running the tests.

TASK-FILES

Operation	Path
modify	`scripts/program-install.sh`
create	`tests/91-install-handler.sh`
modify	`Makefile`
modify	`README.md`
modify	`TODO.md`
modify	`prompts/features/05-pkpass-handler.md`
modify	`prompts/tasks/00-tasks.md`

TASK-VERIFY

Run: make test from the repository root.
Expected: exit status 0, with 91-install-handler reporting ok and the pass type resolving to pkpass-handler.desktop inside the throwaway home.

TASK-FEATURES

prompts/features/05-pkpass-handler.md

TASK-ACCEPTANCE

PKPASS-HANDLER-R021

OUTPUT: the complete files in the order listed, ending with the VERIFICATION: line.