fix: preserve tree-sitter import graph edges

[Rokurolize]

Problem

Tree-sitter dependency graphs compared resolver-produced absolute paths with project-relative discovery keys. Scans could therefore report zero dependency edges and classify imported files as orphaned; a Wikijump JavaScript scan lost all 129 internal edges.

Fix

Resolve discovery keys to absolute paths for parsing and resolver calls while preserving the original keys in graph output. Match imports through separate normalized filesystem identities, retain exact path casing for I/O, resolve relative resolver results against the scan root, and reject duplicate aliases instead of making edge targets input-order-dependent.

Regression coverage includes relative and absolute key lists, a nested project-root versus scan-root collision, simulated Windows normcase behavior, exact resolver arguments, and duplicate aliases in both orders.

Validation

• pytest -q desloppify/tests/lang/common/test_treesitter_imports_direct.py: 15 passed
• pytest -q desloppify/tests/lang/common -k treesitter: 177 passed, 1 skipped
• Full suite: 6,838 passed, 5 skipped; the same two review-prompt assertion failures reproduce on unchanged main
• ruff check . --select E9,F63,F7,F82: passed
• Real Wikijump JavaScript graph: 175 files, 129 edges, 65 files with importers