Add PostCSS configuration and skills lock file

- Created a new PostCSS configuration file to integrate Tailwind CSS.
- Added a skills lock file containing various Expo skills with their respective source and computed hashes.

.agents/skills/building-native-ui/references/controls.md

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+# Native Controls
+
+Native iOS controls provide built-in haptics, accessibility, and platform-appropriate styling.
+
+## Switch
+
+Use for binary on/off settings. Has built-in haptics.
+
+```tsx
+import { Switch } from "react-native";
+import { useState } from "react";
+
+const [enabled, setEnabled] = useState(false);
+
+<Switch value={enabled} onValueChange={setEnabled} />;
+```
+
+### Customization
+
+```tsx
+<Switch
+  value={enabled}
+  onValueChange={setEnabled}
+  trackColor={{ false: "#767577", true: "#81b0ff" }}
+  thumbColor={enabled ? "#f5dd4b" : "#f4f3f4"}
+  ios_backgroundColor="#3e3e3e"
+/>
+```
+
+## Segmented Control
+
+Use for non-navigational tabs or mode selection. Avoid changing default colors.
+
+```tsx
+import SegmentedControl from "@react-native-segmented-control/segmented-control";
+import { useState } from "react";
+
+const [index, setIndex] = useState(0);
+
+<SegmentedControl
+  values={["All", "Active", "Done"]}
+  selectedIndex={index}
+  onChange={({ nativeEvent }) => setIndex(nativeEvent.selectedSegmentIndex)}
+/>;
+```
+
+### Rules
+
+- Maximum 4 options — use a picker for more
+- Keep labels short (1-2 words)
+- Avoid custom colors — native styling adapts to dark mode
+
+### With Icons (iOS 14+)
+
+```tsx
+<SegmentedControl
+  values={[
+    { label: "List", icon: "list.bullet" },
+    { label: "Grid", icon: "square.grid.2x2" },
+  ]}
+  selectedIndex={index}
+  onChange={({ nativeEvent }) => setIndex(nativeEvent.selectedSegmentIndex)}
+/>
+```
+
+## Slider
+
+Continuous value selection.
+
+```tsx
+import Slider from "@react-native-community/slider";
+import { useState } from "react";
+
+const [value, setValue] = useState(0.5);
+
+<Slider
+  value={value}
+  onValueChange={setValue}
+  minimumValue={0}
+  maximumValue={1}
+/>;
+```
+
+### Customization
+
+```tsx
+<Slider
+  value={value}
+  onValueChange={setValue}
+  minimumValue={0}
+  maximumValue={100}
+  step={1}
+  minimumTrackTintColor="#007AFF"
+  maximumTrackTintColor="#E5E5EA"
+  thumbTintColor="#007AFF"
+/>
+```
+
+### Discrete Steps
+
+```tsx
+<Slider
+  value={value}
+  onValueChange={setValue}
+  minimumValue={0}
+  maximumValue={10}
+  step={1}
+/>
+```
+
+## Date/Time Picker
+
+Compact pickers with popovers. Has built-in haptics.
+
+```tsx
+import DateTimePicker from "@react-native-community/datetimepicker";
+import { useState } from "react";
+
+const [date, setDate] = useState(new Date());
+
+<DateTimePicker
+  value={date}
+  onChange={(event, selectedDate) => {
+    if (selectedDate) setDate(selectedDate);
+  }}
+  mode="datetime"
+/>;
+```
+
+### Modes
+
+- `date` — Date only
+- `time` — Time only
+- `datetime` — Date and time
+
+### Display Styles
+
+```tsx
+// Compact inline (default)
+<DateTimePicker value={date} mode="date" />
+
+// Spinner wheel
+<DateTimePicker
+  value={date}
+  mode="date"
+  display="spinner"
+  style={{ width: 200, height: 150 }}
+/>
+
+// Full calendar
+<DateTimePicker value={date} mode="date" display="inline" />
+```
+
+### Time Intervals
+
+```tsx
+<DateTimePicker
+  value={date}
+  mode="time"
+  minuteInterval={15}
+/>
+```
+
+### Min/Max Dates
+
+```tsx
+<DateTimePicker
+  value={date}
+  mode="date"
+  minimumDate={new Date(2020, 0, 1)}
+  maximumDate={new Date(2030, 11, 31)}
+/>
+```
+
+## Stepper
+
+Increment/decrement numeric values.
+
+```tsx
+import { Stepper } from "react-native";
+import { useState } from "react";
+
+const [count, setCount] = useState(0);
+
+<Stepper
+  value={count}
+  onValueChange={setCount}
+  minimumValue={0}
+  maximumValue={10}
+/>;
+```
+
+## TextInput
+
+Native text input with various keyboard types.
+
+```tsx
+import { TextInput } from "react-native";
+
+<TextInput
+  placeholder="Enter text..."
+  placeholderTextColor="#999"
+  style={{
+    padding: 12,
+    fontSize: 16,
+    borderRadius: 8,
+    backgroundColor: "#f0f0f0",
+  }}
+/>
+```
+
+### Keyboard Types
+
+```tsx
+// Email
+<TextInput keyboardType="email-address" autoCapitalize="none" />
+
+// Phone
+<TextInput keyboardType="phone-pad" />
+
+// Number
+<TextInput keyboardType="numeric" />
+
+// Password
+<TextInput secureTextEntry />
+
+// Search
+<TextInput
+  returnKeyType="search"
+  enablesReturnKeyAutomatically
+/>
+```
+
+### Multiline
+
+```tsx
+<TextInput
+  multiline
+  numberOfLines={4}
+  textAlignVertical="top"
+  style={{ minHeight: 100 }}
+/>
+```
+
+## Picker (Wheel)
+
+For selection from many options (5+ items).
+
+```tsx
+import { Picker } from "@react-native-picker/picker";
+import { useState } from "react";
+
+const [selected, setSelected] = useState("js");
+
+<Picker selectedValue={selected} onValueChange={setSelected}>
+  <Picker.Item label="JavaScript" value="js" />
+  <Picker.Item label="TypeScript" value="ts" />
+  <Picker.Item label="Python" value="py" />
+  <Picker.Item label="Go" value="go" />
+</Picker>;
+```
+
+## Best Practices
+
+- **Haptics**: Switch and DateTimePicker have built-in haptics — don't add extra
+- **Accessibility**: Native controls have proper accessibility labels by default
+- **Dark Mode**: Avoid custom colors — native styling adapts automatically
+- **Spacing**: Use consistent padding around controls (12-16pt)
+- **Labels**: Place labels above or to the left of controls
+- **Grouping**: Group related controls in sections with headers