refactor(tests): migrate remaining batches to tests/common/

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.

server/tests/common/mod.rs

@@ -26,7 +26,7 @@ pub mod users;
 // Re-exports for ergonomic `use common::*;` in most test files.
 pub use config::{TestConfig, unique_tmpdir};
 pub use http::{
-    body_json, body_string, csrf_form_post, form_post, get_with_api_key,
+    body_bytes, body_json, body_string, csrf_form_post, form_post, get_with_api_key,
     get_with_api_key_if_none_match, get_with_cookie, header_opt, header_str, multipart_upload_body,
 };
 pub use seed::{