Task: Implement the MIME Association Reader feature

TASK-DESCRIPTION

Create: sources/desktop/mime_association_reader.h
Create: sources/desktop/mime_association_reader.cpp
Create: tests/mime_association_reader_test.cpp
Create: tests/22-mime-association-reader.sh The reader resolves which desktop file opens a MIME type and reports where that answer came from, and implements the requirements in prompts/features/08-mime-association-reader.md. The fallback to mimeinfo.cache must agree with what xdg-mime query default reports for the same type.

TASK-OUTPUT

Produce these complete files in this order, then the VERIFICATION: line: 1. sources/desktop/mime_association_reader.h 2. sources/desktop/mime_association_reader.cpp 3. tests/mime_association_reader_test.cpp 4. tests/22-mime-association-reader.sh

TASK-CONTEXT

The MIME search order is described in documents/12-desktop-loading-and-provenance.md section 4. A missing or unreadable file is skipped without error, and the reader never throws.

TASK-FILES

Operation	Path
create	`sources/desktop/mime_association_reader.h`
create	`sources/desktop/mime_association_reader.cpp`
create	`tests/mime_association_reader_test.cpp`
create	`tests/22-mime-association-reader.sh`

TASK-VERIFY

Run: make test from the repository root.
Expected: exit status 0, and the reported default matches xdg-mime query default when xdg-mime is installed.

TASK-FEATURES

prompts/features/08-mime-association-reader.md

TASK-ACCEPTANCE

MIME-ASSOCIATION-READER-R001
MIME-ASSOCIATION-READER-R002
MIME-ASSOCIATION-READER-R004
MIME-ASSOCIATION-READER-R006
MIME-ASSOCIATION-READER-R007
MIME-ASSOCIATION-READER-R010

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