feat(20-02): add clientTranscripts data layer

schema.ts: clientTranscripts table (id, lead_id/client_id nullable FKs,
title, content NOT NULL, call_date, created_at) + leadsRelations/
clientsRelations updated + clientTranscriptsRelations + TS types.

lead-service.ts: getTranscripts(leadId) — call_date DESC ordering.

actions.ts: addTranscript + deleteTranscript with requireAdmin guard,
Zod validation, and revalidatePath. TypeScript: no errors.

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

src/app/admin/leads/actions.ts

@@ -2,7 +2,8 @@
 
 import { z } from "zod";
 import { db } from "@/db";
-import { leads, quotes, tags } from "@/db/schema";
+import { leads, quotes, tags, clientTranscripts } from "@/db/schema";
+import { nanoid } from "nanoid";
 import { eq, and } from "drizzle-orm";
 import {
   createLeadSchema,
@@ -252,3 +253,58 @@ export async function renameLeadTag(oldValue: string, newValue: string) {
 
   revalidatePath("/admin/leads");
 }
+
+// ── Transcript actions (Phase 20 — KB-02) ────────────────────────────────────
+
+const addTranscriptSchema = z.object({
+  lead_id: z.string().min(1),
+  title: z.string().optional(),
+  content: z.string().min(1, "Il testo del transcript è obbligatorio"),
+  call_date: z.string().regex(/^\d{4}-\d{2}-\d{2}$/, "Data non valida (YYYY-MM-DD)"),
+});
+
+export async function addTranscript(data: z.infer<typeof addTranscriptSchema>) {
+  await requireAdmin();
+
+  const parsed = addTranscriptSchema.safeParse(data);
+  if (!parsed.success) {
+    return { success: false, error: parsed.error.issues[0].message };
+  }
+
+  try {
+    const [transcript] = await db
+      .insert(clientTranscripts)
+      .values({
+        id: nanoid(),
+        lead_id: parsed.data.lead_id,
+        title: parsed.data.title || null,
+        content: parsed.data.content,
+        call_date: parsed.data.call_date,
+      })
+      .returning();
+
+    revalidatePath(`/admin/leads/${parsed.data.lead_id}`);
+    return { success: true, transcript };
+  } catch (error) {
+    console.error("addTranscript error:", error);
+    return { success: false, error: "Errore nel salvataggio del transcript" };
+  }
+}
+
+export async function deleteTranscript(transcriptId: string, leadId: string) {
+  await requireAdmin();
+
+  if (!transcriptId) throw new Error("ID transcript richiesto");
+
+  try {
+    await db
+      .delete(clientTranscripts)
+      .where(eq(clientTranscripts.id, transcriptId));
+
+    revalidatePath(`/admin/leads/${leadId}`);
+    return { success: true };
+  } catch (error) {
+    console.error("deleteTranscript error:", error);
+    return { success: false, error: "Errore nell'eliminazione del transcript" };
+  }
+}