Add developer support for pre-configured AI providers

[jeffpaul]

Description

Enable developers, agencies, and hosts to pre-configure AI providers that will be automatically recognized by the plugin. This supports a “progressive provider selection” approach (where existing providers are utilized and only presents provider configuration needs if no applicable provider has been configured) and reduces the need for manual setup.

Goals

• Define a configuration system (using constants, filters, or configuration files) to allow pre-configured providers.
• Ensure the system is modular so each feature can independently detect and use available providers.
• When a valid pre-configured provider exists, the UI for provider selection should be hidden.
• Document the configuration process with clear examples for hosts and network administrators.
• Align with the encapsulated feature architecture so each feature can extend or override provider handling if needed.

Acceptance Criteria

• Plugin detects and auto-selects any pre-configured providers.
• Provider selection UI is suppressed when configuration is detected.
• Features automatically inherit available provider connections.
• Developer documentation includes at least one working example.

[jeffpaul]

Punting this to v0.2.0, but in chatting with @dkotter there's a question as to whether this should be in the AIE plugin or perhaps in the WP AI Client; @felixarntz @JasonTheAdams any thoughts/preference there?

[JasonTheAdams]

So is the end goal that the AI Experiments plugin is a dependency plugin for others plugin introducing a Provider, as to only have a single settings screen for advanced users to select from?

[jeffpaul]

@JasonTheAdams not sure my brain is able to parse your question, but I would say that the AIE plugin would ideally be able to present options (in an advanced settings mode perhaps) for adding in providers via their respective plugins. We would need a way for AIE to "know" the population of those provider plugins, but that otherwise a user could add those additional providers through AIE.

[JasonTheAdams]

And this is purely for experimentation, right? If a host were to add a Provider is the expectation that they're also integrating with these settings and such?

[justlevine]

Codewise, I would put const/filter handling as close to the code it's related to, so provider settings would live in wp-ai-client, settings-layer stuff would live in AI Experiments. Keeps things composable.

And just because the code lives somewhere shouldnt affect how implements consume it.

I think config files are overkill, if a host want's a config file they can make their own to wrap our const/filters.