Lint checker: stac-check Linter wrapper (checks/lint.py)

[GeoSpark]

Wrap stac-check Linter to emit normative best-practice Findings. See DESIGN.md §6.

Scope

• backend/checks/lint.py: run Linter (best-practices dict); map to Findings (mostly best-practice, some core).
• Carry over config from ../eodh-validator/stac-check.config.yaml (e.g. geometry_coordinates_order: false, max_links, max_properties).

Depends on

#2, #3

Test approach

TDD / integration. Fixtures that trigger known lint messages (missing link titles, non-searchable id, bbox/geometry mismatch); assert mapping.

Acceptance

• Lint messages become Findings with correct category/source.
• Config file honoured.