Fix STAC Item HTML bbox rendering

[BuraakAI]

Overview

STAC Items expose their bounding box as the top-level bbox field, but the HTML template tried to read the Collection-only extent field. This caused every STAC Item HTML page to fail with a Jinja UndefinedError.

This change:

• renders the Item map from the top-level bbox field
• adds a regression test through get_stac_path so the complete API/template path is covered

Related Issue / discussion

Closes #2408

Additional information

The regression test failed against master with the reported missing extent error and passes with this fix.

Validation:

• .venv/bin/pytest -q tests/api/test_stac.py — 7 passed
• .venv/bin/flake8 tests/api/test_stac.py — passed
• .venv/bin/pre-commit run --files pygeoapi/templates/stac/item.html tests/api/test_stac.py — passed
• git diff --check — passed

OpenAI Codex assisted with repository research, the regression test, and the patch. I reviewed the change and validated the failing and passing behavior locally.

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements; no dependencies are changed.

Updates to public demo

• No breaking demo configuration changes are required.

Contributions and licensing

• I would like to contribute this STAC Item HTML bugfix to pygeoapi. I confirm that my contributions are compatible with the pygeoapi license guidelines.