Finishes the lift of shared helpers into `tests/common/`. Covered:
- health, web, oneliners_api, upload (31 tests; upload exercises the
new `multipart_upload_body` helper driven by doctate_common field
constants)
- sse_integration, sse_cleanup, transcribe, oneliner_heal_decoupled,
silent_case_empty, failed_only_case_empty_oneliner,
transient_failure_retries (24 tests)
Also applied cargo fmt across the test tree and fixed one clippy
needless_borrows_for_generic_args warning in analyze_test.
All 387 tests pass; 3 ignored (as before).
Side effect: health_test previously used a hardcoded `/tmp/doctate-test`
data path, which parallel `cargo test` runs could collide on. The
migration replaces it with the common unique-tmpdir pattern, removing
a latent flake.
Lift duplicated test-harness code (User factories, TestConfig builder,
login/CSRF flow, form/json helpers, case-directory seeding, URL path
builders) into `server/tests/common/` so future API changes touch one
file instead of every integration test.
Migrated batches: csrf_attack, auth, login, magic_link, security_headers
(28 tests); analyze, case_page, delete_recording, close_watermark,
retention_sweep (67 tests). All 95 tests still green.
Net line delta across these 10 files: +1113 / -1896 (~780 lines removed),
plus ~500 lines of new shared infrastructure under tests/common/.
Brummel