feat(registratura): auto-detect {proiect} placeholder in subject and switch to template mode

Typing {proiect}, {nr}, {an}, {detalii} or {text} in the subject field
now auto-transforms to template mode with the appropriate input widgets
(project dropdown, number fields, etc.).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/modules/registratura/services/subject-template-service.ts

@@ -589,6 +589,73 @@ export function filterTemplates(
   );
 }
 
+/** Recognized field placeholder names that can be used in dynamic templates */
+const DYNAMIC_FIELD_NAMES = new Set(["nr", "an", "detalii", "proiect", "text"]);
+
+/** Regex to detect at least one valid {fieldName} placeholder */
+const HAS_PLACEHOLDER_RE = /\{(nr|an|detalii|proiect|text)\}/;
+
+/**
+ * Create a dynamic SubjectTemplate from free text containing `{fieldName}`
+ * placeholders.  Recognised names: nr, an, detalii, proiect, text.
+ *
+ * Returns `null` when the text contains no valid placeholder.
+ *
+ * Example:
+ *   createDynamicTemplate("Cerere CU — {proiect}")
+ *   → SubjectTemplate with static "Cerere CU — " + field(proiect)
+ */
+export function createDynamicTemplate(
+  pattern: string,
+): SubjectTemplate | null {
+  if (!HAS_PLACEHOLDER_RE.test(pattern)) return null;
+
+  const tokens: TemplateToken[] = [];
+  const fields: TemplateField[] = [];
+  let fIdx = 0;
+
+  // Split by {fieldName} placeholders (keeping the delimiters)
+  const parts = pattern.split(/(\{[^}]+\})/);
+  for (const part of parts) {
+    if (!part) continue;
+    const fieldMatch = part.match(/^\{(\w+)\}$/);
+    if (fieldMatch) {
+      const name = fieldMatch[1]!;
+      if (!DYNAMIC_FIELD_NAMES.has(name)) {
+        // Unknown placeholder — treat as static text
+        tokens.push({ type: "static", value: part });
+        continue;
+      }
+      const ft = resolveFieldType(name);
+      const field: TemplateField = {
+        id: `f${fIdx}`,
+        name,
+        placeholder: fieldPlaceholder(ft),
+        width: fieldWidth(ft),
+        fieldType: ft,
+        defaultValue: ft === "an" ? CURRENT_YEAR : undefined,
+      };
+      fields.push(field);
+      tokens.push({ type: "field", value: "", field });
+      fIdx++;
+    } else {
+      tokens.push({ type: "static", value: part });
+    }
+  }
+
+  if (fields.length === 0) return null;
+
+  return {
+    id: `dyn_${hashPattern(pattern)}`,
+    pattern,
+    tokens,
+    fields,
+    frequency: 0,
+    exampleSubject: pattern,
+    isSeed: true,
+  };
+}
+
 /**
  * Filter existing subjects by query (plain text substring match).
  * Returns unique matches, limited to `limit`.