add support for OGC API Publish-Subscribe Workflow - Part 1: Core (#2146)

[tomkralidis]

Overview

This PR adds support for OGC API Publish-Subscribe Workflow - Part 1: Core by adding Pub/Sub support (MQTT, HTTP) triggered by item transactions and process execution.

This PR additionally fixes issues found as part of testing (see #2223).

Related Issue / discussion

Fixes #2146
Fixes #2223

Additional information

This implementation is put forth as part of OSGeo contributions to the 2026 Joint OGC – OSGeo – ASF Code Sprint

Dependency policy (RFC2)

• I have ensured that this PR meets RFC2 requirements

Updates to public demo

• I have ensured that breaking changes to the pygeoapi master demo server have been addressed
  • https://github.com/geopython/demo.pygeoapi.io/blob/master/services/pygeoapi_master/local.config.yml

Contributions and licensing

(as per https://github.com/geopython/pygeoapi/blob/master/CONTRIBUTING.md#contributions-and-licensing)

• I'd like to contribute [feature X|bugfix Y|docs|something else] to pygeoapi. I confirm that my contributions to pygeoapi will be compatible with the pygeoapi license guidelines at the time of contribution
• I have already previously agreed to the pygeoapi Contributions and Licensing Guidelines

[webb-ben]

Assume further configuration and tests will come with time

[webb-ben]

+1
Tested against OAProc and received the following from my MQTT broker

@tomkralidis note i continue to receive notifications even if no action happens

[tomkralidis]

+1 Tested against OAProc and received the following from my MQTT broker

@tomkralidis note i continue to receive notifications even if no action happens

Looks like we are not testing for 404s in the underlying repository at the API level. I've put forth a issue in #2223 and associated fix in this PR, including a test in the PostgreSQL provider.

[doublebyte1]

+1 for this. I left some comments, but hope to be able to do more tests

[doublebyte1]

Thank you for adding the AsyncAPI support. It works perfectly 👍🏽