feat(io): route read_file through pre-parse repair by default

Previously only analyze() and direct read_csv_repaired() callers got the
byte-level repair pass (BOM strip, NUL strip, smart-double-quote fold,
unquoted-delimiter merge). The dedup CLI and any other read_file consumer
silently missed it.

read_file gains a repair=True default. CSV/TSV inputs run through
repair_bytes before pandas sees them; Excel inputs still pass through
unchanged. Chunked reads (chunk_size set) bypass repair because the pre-
parse pass loads the whole file — preserving streaming behavior on huge
files. Repair actions and unrepairable lines are logged at INFO/WARNING.

cli_text_clean opts out (repair=False): the cleaner offers fine-grained
control via --preset and per-op flags, and a byte-level smart-quote fold
under the user's "minimal" preset would violate that contract. The
cell-level cleaner does the equivalent work itself when its options ask
for it.

Tests: read_file default strips BOM and folds curly double quotes;
repair=False preserves smart quotes; chunked reads still work and skip
repair as documented.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_io.py

@@ -207,6 +207,40 @@ class TestRepairBytes:
         assert summary.get("strip_nul") == 1
 
 
+class TestReadFileWithRepair:
+    """``read_file(repair=True)`` (default) routes CSV through repair_bytes."""
+
+    def test_default_strips_bom_via_repair(self, tmp_path):
+        f = tmp_path / "bom.csv"
+        f.write_bytes(b"\xef\xbb\xbfid,name\n1,Alice\n")
+        df = read_file(f)
+        # First column header must be 'id', not 'id'.
+        assert list(df.columns)[0] == "id"
+
+    def test_default_folds_smart_double_quotes(self, tmp_path):
+        # Curly quotes are *unquoted* here — outer ASCII quotes would create
+        # a CSV-quoting collision once the fold runs.
+        f = tmp_path / "quoted.csv"
+        f.write_bytes("id,note\n1,curly “hello” world\n".encode("utf-8"))
+        df = read_file(f)
+        assert df.iloc[0]["note"] == 'curly "hello" world'
+
+    def test_repair_false_preserves_smart_quotes(self, tmp_path):
+        f = tmp_path / "quoted.csv"
+        f.write_bytes("id,note\n1,curly “hello” world\n".encode("utf-8"))
+        df = read_file(f, repair=False)
+        assert "“" in df.iloc[0]["note"] or "”" in df.iloc[0]["note"]
+
+    def test_chunked_read_skips_repair(self, tmp_path):
+        # Chunked reads bypass repair (memory budget). Verify they still work.
+        rows = "id,name\n" + "\n".join(f"{i},Alice" for i in range(1, 21))
+        f = tmp_path / "chunked.csv"
+        f.write_text(rows)
+        chunks = list(read_file(f, chunk_size=5))
+        total = sum(len(c) for c in chunks)
+        assert total == 20
+
+
 class TestReadCsvRepaired:
     def test_recovers_malformed_currency_row(self, tmp_path):
         f = tmp_path / "bad.csv"