Polish: clearer errors, corrected docstrings, setuptools pin

- insert/upsert into a name that is actually a view now shows a
  clean error instead of a traceback
- db.view() on a name that is a table now says so in its error
- Database.__getitem__ docstring documents that views are returned
  for view names; hash_id docstring corrected (it is a column name,
  not a boolean)
- Registering two migrations with the same name in one set now
  raises ValueError at registration time instead of executing both
  and failing with IntegrityError at apply time
- build-system requires setuptools>=77, needed for the PEP 639
  license expression

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UnLnhsH25Nnv7LHhekUfPd

tests/test_create.py

@@ -1382,7 +1382,10 @@ def test_bad_table_and_view_exceptions(fresh_db):
     assert ex.value.args[0] == "Table v is actually a view"
     with pytest.raises(NoView) as ex2:
         fresh_db.view("t")
-    assert ex2.value.args[0] == "View t does not exist"
+    assert ex2.value.args[0] == "View t does not exist - t is a table"
+    with pytest.raises(NoView) as ex3:
+        fresh_db.view("missing")
+    assert ex3.value.args[0] == "View missing does not exist"
 
 
 # Tests for issue #655: Table configuration should be stored in _defaults