Persisting context after SSO/Social/Source flow

**Describe your question/**
I've been playing around a bit with flows involving SSO logins, and from what I've gathered any context that is set/created before the SSO login isn't retained through redirect/return to an external IDP. I'm barely remembering something I did a while back to get this to work, but I can't for the life of me find it or remember it now.

The two specific use cases I'm currently trying out are:

### "Source flow" for social/external providers
Setting up a single social application, and then combining it with different authentication flows. Currently, there are two options for this:

1. Setting up an authentication flow and an associated social login (1:1)
2. Setting up an authentication flow and a separate flow for social/source auth, and then redirect the user to the "regular" authentication flow

What I've been trying to accomplish is setting a policy on the "regular" authentication flow ("original_flow") setting something like ``` context["flow_plan"].context["source_flow"] = 'original_flow' ```, so that we can use that to redirect the user back from the social/source auth flow (sso_flow) to the original flow, but it seems that the previous context from before the OIDC login is called is lost/discarded

### Social Invitations
The same goes for invitations paired with social logins. I did find a blog post/github repo that has one way to do it, which depending on the strategy requires a separate set of social login providers for each login flow or even a separate set of social login providers for each login flow and registration/authentication pair.

Am I missing something, or is this how it currently works/is supposed to work?

**Relevant info**
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**Screenshots**
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**Logs**
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**Version and Deployment (please complete the following information):**

- authentik version: 2024.12.1
- Deployment: Tried with both helm & docker-compose

No files, tests, or entry points are named. Start by tracing the SSO, social/source, and external IDP redirect and return flows, then determine where pre-login context is discarded; done should establish and verify the intended handling of context for source flows and social invitations.

Written by the indexing model from the issue text.