Drop the in-app unlock key: only the PRO apk opens PRO

The set is two apks and the unlock key was a second, weaker lock on the
same door. A verifier that runs offline has to carry its secret inside
the lite apk, so anyone who unpacked it could mint a key. Nothing in the
lite build can flip the gate now.

- entitlement.ts keeps the gate (which look is PRO, what an export
  carries in lite) and exports IS_PRO straight from the build flag.
- SETTINGS loses the key field; the plan chip still says LITE / PRO
  ACTIVE and the helper text says what lite cannot export.
- The upsell alerts just name the build that has the feature.
- tools/keygen.mjs goes with the verifier it fed.

src/components/SettingsModal.tsx

@@ -1,5 +1,5 @@
 import React, { useEffect, useState } from 'react';
-import { View, Text, Keyboard, Modal, ScrollView, TouchableOpacity, TextInput } from 'react-native';
+import { View, Text, Keyboard, Modal, ScrollView, TouchableOpacity } from 'react-native';
 import * as Haptics from 'expo-haptics';
 import { X, Volume2, Info, ChevronRight, MapPin, Settings as SettingsIcon } from 'lucide-react-native';
 import { AspectRatio, MeterMode, ShutterSound, StartupMode } from '../types';
@@ -37,11 +37,8 @@ interface SettingsModalProps {
   onGpsEnabled: (enabled: boolean) => void;
   startupMode: StartupMode;
   onStartupMode: (mode: StartupMode) => void;
-  // Lite vs PRO. The unlock key is verified in App (the entitlement module owns
-  // the maths) and comes back false for a bad key, which is all this sheet needs
-  // to know — let alone store.
+  // LITE vs PRO, decided at build time (no key, nothing to enter here).
   pro: boolean;
-  onUnlock: (key: string) => Promise<boolean>;
 }
 
 function ChipRow({ chips }: { chips: Chip[] }) {
@@ -104,11 +101,8 @@ export default function SettingsModal({
   startupMode,
   onStartupMode,
   pro,
-  onUnlock,
 }: SettingsModalProps) {
   const [showCredits, setShowCredits] = useState(false);
-  const [keyDraft, setKeyDraft] = useState('');
-  const [keyError, setKeyError] = useState(false);
   // The RN Modal is its own dialog window, so the IME does not resize it and
   // the card ends up under the keyboard. Track the keyboard height and lift the
   // card by that much instead.
@@ -262,8 +256,8 @@ export default function SettingsModal({
             <CameraOnlyNote cameraMode={cameraMode} />
           </View>
 
-          {/* Lite vs PRO. Every look is free to preview and edit; the key buys
-              the export: no mark, and PRO presets/frames/watermarks allowed. */}
+          {/* LITE vs PRO. Every look is free to preview and edit; the PRO build
+              buys the export: no mark, and PRO presets/frames/watermarks. */}
           <View>
             <SectionLabel>PRO</SectionLabel>
             <ChipRow
@@ -271,42 +265,10 @@ export default function SettingsModal({
                 { key: 'plan', label: pro ? 'PRO ACTIVE' : 'LITE', active: pro, disabled: true, onPress: () => {} },
               ]}
             />
-            {!pro && (
-              <View className="flex-row items-center mt-2">
-                <TextInput
-                  value={keyDraft}
-                  onChangeText={(t) => {
-                    setKeyDraft(t);
-                    setKeyError(false);
-                  }}
-                  placeholder="XXXX-XXXX-XXXX-XXXX"
-                  placeholderTextColor="#52525b"
-                  autoCapitalize="characters"
-                  autoCorrect={false}
-                  className={`flex-1 rounded-md border bg-black/40 px-3 py-2 font-mono text-xs font-bold ${
-                    keyError ? 'border-red-500/70 text-red-400' : 'border-zinc-700 text-zinc-200'
-                  }`}
-                />
-                <TouchableOpacity
-                  onPress={async () => {
-                    haptic();
-                    const ok = await onUnlock(keyDraft);
-                    setKeyError(!ok);
-                    if (ok) setKeyDraft('');
-                  }}
-                  activeOpacity={0.7}
-                  className="ml-2 rounded-md border border-amber-500/70 bg-amber-500/15 px-3 py-2"
-                >
-                  <Text className="font-mono text-[11px] font-bold text-amber-500">UNLOCK</Text>
-                </TouchableOpacity>
-              </View>
-            )}
             <Text className="text-zinc-600 font-mono text-[10px] mt-1.5 ml-1">
-              {keyError
-                ? 'That key is not valid. Check all 16 characters.'
-                : pro
-                  ? 'Every look exports clean: no mark, no limits. Thanks!'
-                  : 'LITE is free forever. Any preset, frame and watermark can be previewed and edited, but a PRO look cannot be exported and every export carries the RECIPESCAM mark. Enter your key to lift both.'}
+              {pro
+                ? 'Every look exports clean: no mark, no limits.'
+                : 'LITE is free forever. Any preset, frame and watermark can be previewed and edited, but a PRO look cannot be exported and every export carries the RECIPESCAM mark.'}
             </Text>
           </View>