fix(pipeline): suppress weak Python member calls

[Enferlain]

What does this PR do?

Fixes #1276.

Python attribute calls were not consistently classified as member calls, allowing weak suffix_match, unique, and field_type_hint resolutions to create false-positive CALLS edges when no import-reachable target existed.

This change marks non-self/cls/super receiver calls as method calls and applies the existing weak-member suppression policy consistently in sequential and parallel resolution. Strong LSP, import, same-module, and service resolutions remain available. Regression coverage exercises extraction plus both pipeline modes.

Verification

• make -f Makefile.cbm test-focused TEST_SUITES='cypher extraction registry pipeline mcp index_resilience'
• Result: 884 passed, 2 skipped

Checklist

• Every commit is signed off (git commit -s) and follows the Contributor License Agreement
• Full test suite passes locally (make -f Makefile.cbm test) — focused sanitized suites passed
• Lint passes (make -f Makefile.cbm lint-ci) — not run locally
• New behavior is covered by regression tests that would fail without this fix