feat: implement dynamic loading of pygeoapi app and improve description formatting

[jirhiker]

Why

This PR addresses the following problem / context:

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How

Implementation summary - the following was changed / added / removed:

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Notes

Any special considerations, workarounds, or follow-up work to note?

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[Copilot]

Pull request overview

This PR updates the pygeoapi mounting integration to dynamically (re)load the pygeoapi.starlette_app module at mount time, and cleans up a handful of long strings/comments for improved formatting consistency.

Changes:

• Added _load_pygeoapi_app() to import or reload pygeoapi.starlette_app and return its APP for mounting.
• Updated mount_pygeoapi() to use the dynamic loader instead of a direct import.
• Reformatted several long description strings and a few long comments/error messages for readability.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
core/pygeoapi.py	Introduces dynamic import/reload of the pygeoapi Starlette app and applies formatting tweaks to long strings/comments.
tests/test_pygeoapi_mount.py	Adds unit tests validating the import-vs-reload behavior of _load_pygeoapi_app().