Unify disabled appearance across all form controls

Disabled controls looked inconsistent: the SearchSelect faded (opacity-50)
while native inputs used a solid strong surface. Standardize on the faded look
(opacity-50) the user preferred, via shared constants so every form element
matches:

- DISABLED_CONTROL_CLASS (disabled:opacity-50 disabled:cursor-not-allowed) on
  the control — native inputs/select/textarea via PrimitiveWidgetsMixin, plus
  the Checkbox component (previously had no disabled style).
- DISABLED_WITHIN_CLASS (has-[:disabled]: wrapper variant) for composite
  controls like SearchSelect whose disabled state lives on an inner element.

e2e asserts a disabled SearchSelect and the Name input fade identically
(opacity 0.5) and return to 1 when enabled. CLAUDE.md documents the shared
disabled constants.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -191,6 +191,7 @@ Pytest settings are in `pyproject.toml` under `[tool.pytest.ini_options]` (`DJAN
 - **Inline Alpine.js** is used for client-side reactivity in domain components (`GameStatusSelector`, `SessionDeviceSelector`). The pattern is `x-data="{...}"` with `fetchWithHtmxTriggers()` for PATCH API calls.
 - **No styling-at-a-distance; elements carry their own classes**: `input.css` is document bootstrapping only (Tailwind import, theme, fonts, resets) — it contains **no form/component styling and no selectors that reach across the DOM** (`#id descendant`, `form input:disabled`, etc.) to style something a component owns. An element's appearance, **including state** (`disabled:`, `has-[:disabled]:`, `focus:`), comes from utility classes on that element, emitted by its component. This keeps state composable (no specificity wars) and robust to markup edits.
 - **Forms render via `FormFields`/`AddForm`, never `form.as_div()`**: `FormFields(form, *, extras=...)` (in `primitives.py`) renders label + control + errors + row layout with their own classes; native controls get their classes from `PrimitiveWidgetsMixin` (`games/forms.py`, which stamps `INPUT/SELECT/TEXTAREA_CLASS` incl. `disabled:` variants by widget type, skipping SearchSelect + checkbox). Every form is on this path, including login (`LoginForm(PrimitiveWidgetsMixin, AuthenticationForm)`). `extras` appends a node into a named field's row (e.g. the session timestamp buttons).
-- **Disabling composite widgets**: a composite widget (e.g. `SearchSelect`) carries its `id` on a wrapper `<div>`, which has no `disabled` state — setting `.disabled` on it is a no-op. Disable the inner control (for `SearchSelect`, the `[data-search-select-search]` input); the **component owns its disabled *look*** via `has-[:disabled]:` utilities on its container class, so callers toggle only the control's `disabled`, never styles.
+- **Disabled form controls share one look**: every form element fades the same way when disabled, via the shared constants in `primitives.py` — `DISABLED_CONTROL_CLASS` (`disabled:opacity-50 disabled:cursor-not-allowed`, put on the control: native inputs via the mixin, `Checkbox`, etc.) and `DISABLED_WITHIN_CLASS` (the `has-[:disabled]:` wrapper variant, for composite controls like `SearchSelect` whose disabled state lives on an inner element). Reuse these constants; don't hand-roll a different disabled style per control.
+- **Disabling composite widgets**: a composite widget (e.g. `SearchSelect`) carries its `id` on a wrapper `<div>`, which has no `disabled` state — setting `.disabled` on it is a no-op. Disable the inner control (for `SearchSelect`, the `[data-search-select-search]` input); the wrapper fades itself via `DISABLED_WITHIN_CLASS`, so callers toggle only the control's `disabled`, never styles.
 - **Platform icons** are SVG snippets in `games/templates/icons/<slug>.html`. Add new ones there and reference them by slug in `Platform.icon`.
 - **Name compound types explicitly** — if a `tuple`, `dict`, or other compound value is passed between functions or appears in multiple signatures, give it a named type (`TypedDict`, `NamedTuple`, or a `type` alias) rather than repeating the structural annotation. This applies even to small types used in only a few places; the name carries intent that the structure cannot. Examples: `LabeledOption = tuple[str, str]` instead of repeating `tuple[str, str]` for (value, label) pairs; `RangeValues(min, max)` instead of `tuple[str, str]` for range bounds.