python: an imported module-level instance types its receiver across the module boundary (#1140)

[swapnilpaliwal-sd]

Closes the residual of #1140. The external weekly report measured this shape at 22.4% of in-repo call sites unresolved in a Python repo vs 6.7% in the same repo rewritten in TypeScript, with the singleton idiom (from svc.order_service import order_service) as the named repro.

What was still broken after #1143

1. When the imported value's name collides with its module's last segment — the ordinary way a singleton is written — the member-vs-submodule fallback suffix-matched the target module itself, resolved the import as MODULE with an empty hash, and the python/parser: resolve a from-import of a module-level value to VARIABLE, not MODULE (#1140) #1143 VARIABLE branch never ran.
2. Even where python/parser: resolve a from-import of a module-level value to VARIABLE, not MODULE (#1140) #1143 did fire, nothing consumed the resolved binding: the importing module's local type index never learned the exported binding's inferred type, so the call still fell to a name match.
3. The engine re-derives resolution independently and had no rule for VARIABLE imports at all.

The fix

• parser: module-level variables count as declared members ahead of the submodule fallback; a "submodule" that IS the target module is rejected; the per-module local type index is built for all modules first, then a VARIABLE-import binding copies the exporting binding's type.
• engine: binding_value_type gains the mirror clause over import_binding + import_resolved_target("VARIABLE", …).

Evidence

• Suite 43/43 green. New case 43-module-singleton-import pins the colliding and non-colliding shapes plus a genuine-submodule control (all known_edge). Cases 21/42 re-blessed: +4 known_edge, the untyped_receiver:local_untyped reason disappears, nothing demoted.
• Parse-level A/B on three corpus projects: 621 call sites gain a resolved callee, zero lose one; 234 imports flip MODULE('') → VARIABLE(hash). The only label-only churn is hashless IMPORTED → hashless UNRESOLVED on receivers that were previously mislabeled as module imports.
• Engine-level A/B on one subject: 18 placeholder rows (ambiguous_unknown/boundary_lib) replaced by 24 known_edge rows; no known_edge or multi_inferred lost; solve 53s → 42s.