Add Route nodes and HANDLES edges for DRF ViewSet actions

[muskiteer]

What does this PR do?

This PR adds support for indexing Django REST Framework ViewSet actions decorated with @action by emitting Route nodes and Route-[:HANDLES]->Method relationships.

Previously, DRF action methods were indexed only as Method nodes, which meant endpoint inventory and endpoint-to-handler mapping were incomplete for projects using DRF routers.

Changes

• Emit Route nodes for DRF @action methods.
• Populate route metadata (HTTP method, path, source, and file path where available).
• Create Route-[:HANDLES]->Method relationships linking routes to their corresponding handler methods.
• Preserve existing Method extraction.

Verification

Reproduced using a minimal Django REST Framework project:

class CustomerTaskAdminViewSet(ViewSet):
    @action(detail=True, methods=["post"])
    def approve_draft_with_charge(self, request, pk=None):
        ...

Before:

• Method node was present.
• No Route nodes were emitted.
• No Route-[:HANDLES]->Method relationships existed.

After:

• Route node is emitted.
• Route-[:HANDLES]->Method relationship is created.
• Route metadata is available for the action.

Checklist

• Every commit is signed off (git commit -s) — required, CI rejects unsigned commits (DCO, see CONTRIBUTING.md)
• Tests pass locally (make -f Makefile.cbm test)
• Lint passes (make -f Makefile.cbm lint-ci)
• New behavior is covered by a test (reproduce-first for bug fixes)

Fixes #603

[muskiteer]

Hi @DeusData,
I've opened a PR for the DRF ViewSet route extraction changes.

While testing locally, I ran into some issues with the test and lint targets. From what I could tell, these didn't appear to be directly related to the changes in this PR, but please let me know if I missed something.

I'd really appreciate any feedback or suggested changes. Happy to update the PR if needed.

Thanks