feat(godot): resolve autoload access cross-file (L7 finalization)

[sunerpy]

Summary

Cross-file finalization for Godot — the headline capability that turns autoload usage into real edges so an autoload-only-called function is no longer false dead-code.

• Autoload access resolution: GDScript BuffManager.apply() (where BuffManager is a [autoload] singleton from project.godot) now resolves to that singleton via the resolver's resolve() Strategy-1, gated strictly by the known autoload roster — non-roster receivers (Vector2.ZERO, locals) yield no edge. Zero false positives by construction.
• Architecture note: post_extract returns nodes-only (cannot create edges), so autoload edges are produced in resolve(); post_extract does the nodes-only work (stamps the singleton's signature with its confirmed script binding when the script file exists). Scene→script and signal-connection handlers resolve via the existing generic name-matcher (not duplicated).
• L3's parse_gdscript_dynamics is untouched; parse_autoload_candidates is added alongside and merged into the .gd extract; the DYNAMIC_PREFIX sentinel refs are skipped.

Verification

• make ci green; godot suites green (project 8, scene 8, resource 7, script 21, post_extract 5, frameworks 28); workspace 0 failures; clippy -D warnings 0; guardrail 0; golden corpora byte-unchanged.
• No new EdgeKind/NodeKind, no new dependency.