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>

tests/test_pattern_coverage.py

@@ -149,6 +149,21 @@ def test_largest_gaps_ranks_by_unclassified_and_drops_clean_dirs():
     assert gaps == [{"dir": "src", "unclassified": 2, "total": 3}]
 
 
+def test_type_import_specifiers_are_not_definitions():
+    """#2904: `import { type Foo, bar }` is the same two words as `type Foo =`
+    and defines nothing; only a `type` line with a declaration after the
+    name counts (TS alias, Go/Rust type)."""
+    from scribe.services.coverage import extract_shapes
+    src = (
+        'import { type DesignSystem, fetchDesignSystems } from "@/api/designSystems";\n'
+        'import { type Project } from "./x";\n'
+        "type Baz = { a: number };\n"
+        "type Wide<T> = T | null;\n"
+        "type Point struct {\n\tX int\n}\n"
+    )
+    assert extract_shapes(src) == [("sym", "Baz"), ("sym", "Wide"), ("sym", "Point")]
+
+
 def test_coverage_line_is_evidence_carrying_and_labeled_estimate():
     line = coverage_line({
         "total": 4573, "accounted": 3100, "unclassified": 1473,