Keep a central test tree, organized per module

Context¶

ARCHITECTURE_RULES §9 asks for tests to live inside the module they cover, mirroring its structure, so the module layout also removes test fan-out. The existing suite is a single top-level tests/ tree that is green (176 tests). Relocating every test into src/docir/modules/** in the same change as the structural refactor multiplies the churn and the chance of breakage.

Decision¶

Keep the central tests/ tree for now, but organize it to mirror the module structure — tests/modules/{documents,tags,indexing}/, tests/platform/, tests/entry_points/ — so each test's owning context is unambiguous. Defer co-locating tests inside src/docir/modules/** to a later, isolated change.

Consequences¶

• Easier: the refactor lands without touching test bodies; ownership is still legible from the directory a test lives in.
• Harder: tests are not yet physically inside their module, so a module is not fully self-contained per §9.
• This is a recorded deviation from §9 (a SHOULD/MUST on test location); moving the tests into the modules is the sanctioned follow-up that supersedes it.