refactor(tests+frontend): one http_sink helper for the hook tests; apiErrorMessage replaces ten hand-rolled error-body parses; type X, import specifiers are not definitions (#2904, milestone 299 step 6)

tests/helpers.http_sink replaces three module-local _Sink handlers (the
write-path tests and the after-write test). ProjectView + SettingsView
parsed `(e as {body?:{error?}}).body?.error || fallback` by hand ten times
beside the apiErrorMessage canon (#2853) - all ten now call it. The
extractor (server + the hook awk mirror) no longer reads `import { type Foo }`
as a definition of Foo - that was the last "identical body" sym family.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/services/coverage.py

@@ -123,6 +123,12 @@ def _definition_on(raw: str) -> tuple[str, str] | None:
         name = m.group(1)
         if name.startswith("__") and name.endswith("__"):
             return None
+        # `type` announces a definition only when something is declared after
+        # the name (`type Foo = …`, `type Foo struct {`); an import specifier
+        # (`import { type Foo, bar }`) is the same two words and defines
+        # nothing — it showed up as a two-file "identical body" family (#2904).
+        if line.startswith("type") and not re.search(r"[={]", line[m.end():]):
+            return None
         return ("sym", name)
     if m := _ARROW_RE.match(line):
         return ("sym", m.group(1))