fix(resolver): resolve calls through absolute Python imports

[protereus]

Summary

Resolves calls made through absolute Python imports of first-party modules (from shop.pricing import apply_discount; apply_discount()) to the function or class they name, instead of a dep:: stub. Until now these calls were lost from the graph, so get_callers, get_test_targets and analyze kind=untested missed them. Pytest files import the code under test this way, so on Python repos most tested functions were reported untested.

Fixes #824.

Changes

• internal/resolver/python_absolute_imports.go: resolvePythonModuleExtern, called at the top of resolveExtern. It runs only for .py/.pyi callers whose extern import path is dotted (no /), and tries the two readings the Python extractor produces:

  1. the symbol defined in the module the path names: shop.pricing::apply_discount, from import shop.pricing as p; p.apply_discount() or from shop import pricing; pricing.apply_discount();
  2. the path's last segment defined in its parent module: shop.pricing.apply_discount::apply_discount, from from shop.pricing import apply_discount. The local name is ignored, so import ... as alias resolves too.

  A module a.b matches a/b.py, a/b.pyi or a/b/__init__.py, at the root or under a source root / repo prefix (src/a/b.py). Only KindFunction / KindType candidates count, because an import binds module attributes and never class members. The step resolves only on a unique match: when the module exists in more than one repo, it prefers the caller's repo; two same-repo matches (a src/ and a build/lib/ copy, say) are left unresolved rather than guessed. Anything it doesn't resolve falls through to the existing directory match unchanged.

• internal/resolver/resolver.go: the hook, plus callerRepo hoisted above it so the Python step and Pass 1 share one lookup.

• internal/resolver/repo_language_lookup.go: warmRepoLanguageNameCache also warms the imported name (reading 2) for Python extern edges, so the step doesn't add a store round-trip per edge.

• internal/resolver/python_absolute_imports_test.go: a table test for the module/file matcher, plus resolveExtern tests for from-import, alias, class, module-attribute call, package __init__.py, methods ignored, wrong module, third-party, ambiguous layout, caller-repo preference, and a Go caller left untouched.

• internal/indexer/python_absolute_import_test.go: TestIndex_PythonAbsoluteImportCallsResolve, end to end through the real extractor: a src/-layout package and a pytest file using a plain import, an alias, a module attribute and a class. Each test function must get both calls and tests edges to the first-party definition.

Effect

On the two public src/-layout projects from #824 (Python extractor only, in-process indexing):

	requests before	requests after	click before	click after
first-party calls edges landing on dep:: stubs	171	33	416	133
src/ functions + methods with an EdgeTests edge	32 / 268	63 / 268	72 / 583	82 / 583
index time	0.6 s	0.6 s	0.9 s	1.0 s

What remains is mostly re-exports through a package __init__.py (click's tests call click.echo, which click/__init__.py re-imports from click.utils). As noted in the issue, that case is out of scope here.

Testing

• All tests pass (go test -race ./...), with the scope noted below
• New tests added for new functionality
• Benchmarks run if performance-relevant: not run. The step adds one warmed name per Python extern edge and a path check per candidate; index time on the two projects above is unchanged within noise.

go test -race passes on ./internal/resolver/, ./internal/parser/languages/, ./internal/analysis/ and ./internal/entrypoints/. I ran the affected packages rather than the full suite. In ./internal/indexer/, everything passes except TestBuildCommitLayerNeverFetchesPromisedRenameBlobs, the promisor-fixture test that also fails on unmodified main on this machine (local git 2.43.0), as noted in #796. golangci-lint v2.13.1 reports 0 issues on ./internal/resolver/ and ./internal/indexer/. With the hook removed, the six positive resolver tests and the indexer test fail; the negative cases (methods, wrong module, third-party, ambiguous, Go caller) pass either way, as they should.

Checklist

• Code follows existing patterns in the codebase: a language-specific pass in its own file, like relative_imports.go, and extractor-backed indexer tests like the Pydantic and Alembic ones
• No unnecessary abstractions added
• Language extractor includes Meta["methods"] for interfaces (if applicable): n/a
• Methods have EdgeMemberOf edges to their containing type (if applicable): n/a

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