[schema] Emit unit for float fields; leave union validators untyped

Address review feedback:
- float_with_unit fields now dump as type "float" with the canonical unit
  (e.g. {"type": "float", "unit": "Hz"}) rather than the quantity name as the
  type. This keeps the type vocabulary closed and lets editors label the field
  with its unit directly instead of mapping each quantity name. The unit is the
  first alternative of the accepted-units regex; current/voltage list A/V first
  (no validation change).
- Drop scalar typing of validate_bytes and date_time: both accept multiple YAML
  forms (unit-suffixed strings or numbers, and a formatted string or a mapping)
  that a single scalar type would wrongly reject in the editor.

tests/script/test_build_language_schema.py

@@ -333,7 +333,6 @@ def _convert(validator: object) -> dict:
         (cv.directory, "string"),
         (cv.mqtt_qos, "integer"),
         (cv.hex_int, "integer"),
-        (cv.validate_bytes, "integer"),
         (cv.percentage, "float"),
         (cv.temperature, "float"),
         (cv.color_temperature, "float"),
@@ -378,28 +377,32 @@ def test_convert_scalar_schema_extractor(scalar: str) -> None:
         del ejs.hidden_schemas[repr(decorated)]
 
 
-def test_convert_float_with_unit_uses_quantity_as_type() -> None:
-    """A float schema_extractor whose probe returns a quantity types by quantity."""
+def test_convert_float_with_unit_reports_unit() -> None:
+    """A float schema_extractor whose probe returns a unit types float + unit."""
     import voluptuous as vol
 
     from esphome import schema_extractors as ejs
 
     def frequency_validator(value: object) -> object:
-        return "frequency" if value is ejs.SCHEMA_EXTRACT else value
+        return "Hz" if value is ejs.SCHEMA_EXTRACT else value
 
     ejs.hidden_schemas[repr(frequency_validator)] = "float"
     try:
-        assert _convert(frequency_validator).get("type") == "frequency"
+        entry = _convert(frequency_validator)
+        assert entry.get("type") == "float"
+        assert entry.get("unit") == "Hz"
     finally:
         del ejs.hidden_schemas[repr(frequency_validator)]
 
-    # A float source that does not name a quantity falls back to "float".
+    # A float source with no unit is a bare float (no unit key).
     def plain_float(value: object) -> object:
         return None if value is ejs.SCHEMA_EXTRACT else value
 
     ejs.hidden_schemas[repr(plain_float)] = "float"
     try:
-        assert _convert(plain_float).get("type") == "float"
+        entry = _convert(plain_float)
+        assert entry.get("type") == "float"
+        assert "unit" not in entry
     finally:
         del ejs.hidden_schemas[repr(plain_float)]
 
@@ -461,13 +464,14 @@ def test_cv_types_end_to_end(full_schema_dir: Path) -> None:
     ]["config_vars"]["abbwelcome"]["schema"]["config_vars"]
     assert abbwelcome["message_type"]["type"] == "integer"
 
-    # cv.All(cv.frequency, cv.float_range(45, 66)) -> quantity type + min/max
+    # cv.All(cv.frequency, cv.float_range(45, 66)) -> float + unit + min/max
     # inline, next to type.
     ade = json.loads((full_schema_dir / "ade7880.json").read_text())
     freq = ade["ade7880.sensor"]["schemas"]["CONFIG_SCHEMA"]["schema"]["config_vars"][
         "frequency"
     ]
-    assert freq["type"] == "frequency"
+    assert freq["type"] == "float"
+    assert freq["unit"] == "Hz"
     assert freq["min"] == 45.0
     assert freq["max"] == 66.0