Fix all clippy warnings in space roles files: dangerous `as` casts,
`to_string()` on &str, format string inlining, items-after-statements,
needless borrows, large futures, semicolons outside blocks, and
let-else patterns.
Extract `compute_user_power_level` and `roles_satisfy_requirements` as
pure free functions so the core logic can be unit-tested without async
service dependencies. Update all tests in tests.rs and
integration_tests.rs to call the real extracted functions instead of
reimplementing the logic inline.
Add negative deserialization tests for RoleDefinition,
SpaceRoleMemberEventContent, and SpaceRoleRoomEventContent. Improve
doc comments on handle_* methods and add module-level documentation to
cache_tests.rs.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
ember33
dd1e9f0979