fix: phone leak, field-by-value detection, strict Flamingo email fallback

Three pilot-surfaced issues in one pass:

1. PhoneParser regex used '\s' in the candidate character class, so a
   digit on a following flattened line bled into the phone. '+7977
   6277470\n1' (phone + trailing checkbox value) parsed as 12 digits,
   producing '+797762774701'. Replaced '\s' with a literal space so
   newlines/tabs stop the candidate.

2. Custom-themed forms don't use 'your-name' / 'your-email' keys
   (washanyanya.ru has text-211 / text-212 / name_user). Added
   FieldDetector::find_name + find_email as fallbacks. Classifier
   and MessageFormatter now call them if no standard key matches,
   so 'Александр' in text-211 is recognised as a cyrillic name and
   scored / displayed accordingly.

3. FlamingoHelper copied '_from_email' into 'your-email' without
   validating it. Flamingo derives that meta from whatever field it
   considers "first"; on phone-first forms it ends up holding the
   phone number. Now we only copy _from_email if it contains '@',
   and dropped the _from_name shortcut entirely — FieldDetector
   handles the name via the actual field values.

Tests: +1 FieldDetectorTest (13 cases); +2 PhoneParserTest cases for
newline/tab bleeds; +1 ClassifierTest case; +1 MessageFormatterTest
case for custom field keys. Full suite 53/53 green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/ClassifierTest.php

@@ -154,4 +154,21 @@ final class ClassifierTest extends TestCase
         }
         self::assertTrue($matched);
     }
+
+    public function test_detects_cyrillic_name_under_custom_field_key(): void
+    {
+        // Real form on washanyanya.ru uses keys like 'text-211' / 'text-212'
+        // instead of 'your-name' / 'your-tel'. Classifier must still award
+        // +1 for a cyrillic name via the value-based heuristic.
+        $fields = [
+            'text-211' => 'Александр',
+            'text-212' => '+79776277470',
+        ];
+        $r = Classifier::classify($fields, ['reason' => 'Akismet']);
+        $has_name = false;
+        foreach ($r['reasons'] as $reason) {
+            if (strpos($reason['text'], 'кириллическое имя') !== false) $has_name = true;
+        }
+        self::assertTrue($has_name, 'expected +1 кириллическое имя via value heuristic');
+    }
 }