Fix Live Activity lock screen rendering and polish multi-account auth.

Flatten widget layouts and use system colors so banner and expanded regions render on vibrant lock screens; migrate auth sessions per account to prevent double sign-in; scope app lock PIN to accounts; default clock description to "Clock In"; add architecture docs and deferred form validation on auth screens.

Co-authored-by: Cursor <cursoragent@cursor.com>

components/clients/ClientForm.tsx

@@ -15,6 +15,7 @@ import { Input } from "@/components/ui/Input";
 import { fonts, spacing } from "@/constants/theme";
 import type { ThemeColors } from "@/lib/theme-palette";
 import { useThemedStyles } from "@/lib/use-themed-styles";
+import { isRequiredString, parseNonNegativeNumber } from "@/lib/form-validation";
 import { api } from "@/lib/trpc";
 
 export type ClientFormValues = {
@@ -124,10 +125,7 @@ export function ClientForm({
   }
 
   function handleSave() {
-    if (!values.name.trim()) {
-      setFieldError("Name is required");
-      return;
-    }
+    if (!canSave) return;
 
     const rate = values.defaultHourlyRate.trim()
       ? Number(values.defaultHourlyRate)
@@ -178,6 +176,13 @@ export function ClientForm({
 
   const saving = createClient.isPending || updateClient.isPending;
 
+  const nameError = values.name.trim() ? undefined : "Name is required";
+  const rateError =
+    values.defaultHourlyRate.trim() && parseNonNegativeNumber(values.defaultHourlyRate) === null
+      ? "Hourly rate must be a valid number"
+      : undefined;
+  const canSave = isRequiredString(values.name) && !rateError;
+
   return (
     <KeyboardAvoidingView
       behavior={Platform.OS === "ios" ? "padding" : undefined}
@@ -190,7 +195,13 @@ export function ClientForm({
         keyboardShouldPersistTaps="handled"
       >
         <Card title="Contact">
-          <Input label="Name" value={values.name} onChangeText={(v) => patch("name", v)} />
+          <Input
+            label="Name"
+            value={values.name}
+            onChangeText={(v) => patch("name", v)}
+            required
+            error={nameError}
+          />
           <Input
             label="Email"
             value={values.email}
@@ -238,6 +249,7 @@ export function ClientForm({
             onChangeText={(v) => patch("defaultHourlyRate", v)}
             keyboardType="decimal-pad"
             placeholder="Optional"
+            error={rateError}
           />
           <Input
             label="Currency"
@@ -254,6 +266,7 @@ export function ClientForm({
           <Button
             title={mode === "create" ? "Create client" : "Save changes"}
             loading={saving}
+            disabled={!canSave}
             onPress={handleSave}
           />
           {mode === "edit" ? (