fix(events): prevent autoplan module recursion cycles

[krewenki]

what

• Add cycle protection to module autoplanning graph builder so self-referential and cyclic modules don’t recurse forever.
• Include fixtures for self-import and mutual module cycles and add regression tests to modules_test.go.
• Keep project membership propagation intact while short-circuiting revisits.

why

• Autoplan module indexing was re-entering already-loaded modules, leading to stack overflows when a module imported itself or formed a cycle.
• Cycle guard plus regression tests prevent the crash and cover both self and mutual dependency cases.

tests

• GOCACHE=/Users/warren.krewenki/src/.gocache go test ./server/events -count=1

references

• closes Autoplan module indexing stack overflows when a module imports itself #6024

[krewenki]

@lukemassa - Thanks for the review. I wanted to clarify: Is there anything else for me to do here or will it be merged by someone on the team when they're ready to incorporate it?

[lukemassa]

@lukemassa - Thanks for the review. I wanted to clarify: Is there anything else for me to do here or will it be merged by someone on the team when they're ready to incorporate it?

Nothing from me; at this point a maintainer will either merge or comment with questions/concerns