Require a name and birth year for every student

Both fields are marked in their labels the same way a required registration
question is, and enforced on the server whichever form they arrive from:
GuardianService::createChild() and updateChild() now refuse a blank name or
an unusable birth year, and the signup form checks the same rule up front,
before it creates a single user, so a bad block never leaves a
half-registered family behind. normaliseBirthYear() became public and static
so both paths share one definition of what a usable year is.

The signup form cannot lean on the browser here. Its child blocks are hidden
until the parent/guardian box is ticked, and a `required` field inside a
hidden container makes the whole form unsubmittable with no control the user
can reach to fix — the same trap the guardian's own question panel already
sidesteps by disabling rather than hiding. So register.js puts `required` on
and takes it off along with the block itself, and the server is what makes
the rule hold with JavaScript off. The profile screen has no such problem:
its forms are always visible, so the attribute is static there.

One behaviour change beyond the requirement: a child block with anything
typed into it is now reported back instead of dropped. Previously any block
without a name was silently discarded, which would now mean losing a birth
year the guardian had filled in. A wholly untouched spare block — the one
the form always renders for "add another" — is still ignored.

Verified the required-toggling in a headless browser: unticked submits,
ticked blocks an empty block, a cloned block inherits the requirement, and
re-unticking leaves nothing behind to block a non-guardian signup.

Closes #148

Co-Authored-By: Claude Opus 5 <[email protected]>

templates/frontend/family-page.php

@@ -38,12 +38,12 @@ if (! defined('ABSPATH')) {
                             <input type="hidden" name="us_family_action" value="edit">
                             <input type="hidden" name="child_id" value="<?php echo esc_attr((string) $child['id']); ?>">
                             <p>
-                                <label for="us-edit-name-<?php echo esc_attr((string) $child['id']); ?>"><?php esc_html_e('Name', 'unsupervised-schedular'); ?></label>
+                                <label for="us-edit-name-<?php echo esc_attr((string) $child['id']); ?>"><?php esc_html_e('Name', 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
                                 <input type="text" name="child_name" id="us-edit-name-<?php echo esc_attr((string) $child['id']); ?>" value="<?php echo esc_attr($child['name']); ?>" required>
                             </p>
                             <p>
-                                <label for="us-edit-birth-year-<?php echo esc_attr((string) $child['id']); ?>"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?></label>
-                                <input type="number" name="child_birth_year" id="us-edit-birth-year-<?php echo esc_attr((string) $child['id']); ?>" value="<?php echo esc_attr($child['birth_year']); ?>" min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
+                                <label for="us-edit-birth-year-<?php echo esc_attr((string) $child['id']); ?>"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
+                                <input type="number" name="child_birth_year" required id="us-edit-birth-year-<?php echo esc_attr((string) $child['id']); ?>" value="<?php echo esc_attr($child['birth_year']); ?>" min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
                             </p>
                             <p>
                                 <button type="submit"><?php esc_html_e('Save', 'unsupervised-schedular'); ?></button>
@@ -76,12 +76,12 @@ if (! defined('ABSPATH')) {
 
         <h4><?php esc_html_e('Add a student', 'unsupervised-schedular'); ?></h4>
         <p>
-            <label for="us-child-name"><?php esc_html_e('Name', 'unsupervised-schedular'); ?></label>
+            <label for="us-child-name"><?php esc_html_e('Name', 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
             <input type="text" name="child_name" id="us-child-name" required>
         </p>
         <p>
-            <label for="us-child-birth-year"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?></label>
-            <input type="number" name="child_birth_year" id="us-child-birth-year" min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
+            <label for="us-child-birth-year"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
+            <input type="number" name="child_birth_year" id="us-child-birth-year" required min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
         </p>
         <p>
             <label for="us-child-relationship"><?php esc_html_e('Your relationship to them', 'unsupervised-schedular'); ?></label>

templates/frontend/register-page.php

@@ -86,12 +86,12 @@ if (! defined('ABSPATH')) {
                             <?php /* The first block is the template the "Add another student" button clones. */ ?>
                             <div class="us-child" data-child-index="0">
                                 <p>
-                                    <label for="us-child-0-name"><?php esc_html_e("Student's name", 'unsupervised-schedular'); ?></label>
-                                    <input type="text" name="children[0][name]" id="us-child-0-name">
+                                    <label for="us-child-0-name"><?php esc_html_e("Student's name", 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
+                                    <input type="text" name="children[0][name]" id="us-child-0-name" aria-required="true" data-us-child-required>
                                 </p>
                                 <p>
-                                    <label for="us-child-0-birth-year"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?></label>
-                                    <input type="number" name="children[0][birth_year]" id="us-child-0-birth-year" min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
+                                    <label for="us-child-0-birth-year"><?php esc_html_e('Birth year', 'unsupervised-schedular'); ?> <span class="us-required" aria-hidden="true">*</span></label>
+                                    <input type="number" name="children[0][birth_year]" id="us-child-0-birth-year" aria-required="true" data-us-child-required min="1900" max="<?php echo esc_attr(current_time('Y')); ?>" step="1" inputmode="numeric" placeholder="<?php esc_attr_e('YYYY', 'unsupervised-schedular'); ?>">
                                 </p>
                                 <?php foreach ($accountQuestions as $question) : ?>
                                     <?php