fix(kanban): one undecodable task field no longer breaks the whole board listing

A tasks row whose TEXT body holds invalid UTF-8 made sqlite3 raise
"Could not decode to UTF-8 column 'body'" inside fetchall, so `hermes kanban
list` (and `show`, and every other reader of that row) failed board-wide
until the row was deleted by hand; a BLOB-typed body came back as bytes and
crashed `--json` (#111743).

Fix it once at the connection: every board connection (`_open_configured`
and the read-only descendant path in `connect`) installs a lossy
text_factory that substitutes U+FFFD, and `Task.from_row` runs BLOB cells
through the same helper so a corrupt row renders with replacement
characters instead of taking its neighbours down.

Fixes #111743

tests/hermes_cli/test_kanban_list_undecodable_text.py

@@ -0,0 +1,54 @@
+"""Invariant: one task row with an undecodable text field cannot take down the
+board listing (issue #111743).
+
+A ``body`` stored as TEXT holding invalid UTF-8 made sqlite3 abort the whole
+``fetchall`` ("Could not decode to UTF-8 column 'body'"), so ``hermes kanban list``
+failed for every card until the row was deleted by hand; a BLOB-typed body came
+back as ``bytes`` and crashed ``--json``. Board connections now decode lossily
+(U+FFFD) and ``Task.from_row`` coerces BLOB cells the same way.
+"""
+
+from __future__ import annotations
+
+import dataclasses
+import json
+from pathlib import Path
+
+import pytest
+
+from hermes_cli import kanban_db as kb
+from hermes_cli import kanban_db_connect as kbc
+
+
+@pytest.fixture
+def board(tmp_path, monkeypatch):
+    home = tmp_path / ".hermes"
+    home.mkdir()
+    monkeypatch.setenv("HERMES_HOME", str(home))
+    monkeypatch.setattr(Path, "home", lambda: tmp_path)
+    db_path = kb.kanban_db_path(board="default")
+    kb._INITIALIZED_PATHS.discard(str(db_path.resolve()))
+    kb.init_db()
+    return db_path
+
+
+def test_list_survives_undecodable_and_blob_text_cells(board):
+    with kbc.connect() as conn:
+        good = kb.create_task(conn, title="good card", assignee="coder")
+        conn.execute(
+            "INSERT INTO tasks (id, title, body, assignee, status, priority, created_by, created_at) "
+            "VALUES ('t_text_bad', 'text invalid', CAST(X'FFFEABCD00' AS TEXT), 'coder', 'ready', 0, 'user', 1000)"
+        )
+        conn.execute(
+            "INSERT INTO tasks (id, title, body, assignee, status, priority, created_by, created_at) "
+            "VALUES ('t_blob_bad', 'blob body', X'FFFEABCD00', 'coder', 'ready', 0, 'user', 1000)"
+        )
+
+    with kbc.connect() as conn:
+        tasks = {t.id: t for t in kb.list_tasks(conn, status="ready")}
+        assert {good, "t_text_bad", "t_blob_bad"} <= set(tasks)
+        for tid in ("t_text_bad", "t_blob_bad"):
+            body = tasks[tid].body
+            assert isinstance(body, str) and "\ufffd" in body
+            json.dumps(dataclasses.asdict(tasks[tid]))  # the --json path
+        assert kb.get_task(conn, "t_text_bad").title == "text invalid"