Remove recordings feature, replay sessions directly, bump to 0.6.0

Recordings were just a thin named pointer over an already-captured
session's events, so the whole separate feature (recordings table, API
routes, pages, UI) is gone: any completed session can now be named and
replayed directly. Replaying no longer creates a session or duplicates
events of its own - it just bumps the source session's playCount/lastPlayedAt.

Also renames play_sessions/playSession(s) to sessions/session(s) throughout
the schema, queries, API routes, and UI for consistency, and updates the
README to match the new flow.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

app/api/sessions/[id]/events/route.ts

@@ -0,0 +1,28 @@
+import { NextResponse } from "next/server";
+import { z } from "zod";
+import { insertEvents } from "@/lib/db/queries/session-events";
+import { withRouteLogging } from "@/lib/api/with-route-logging";
+
+const eventSchema = z.object({
+  sessionDeviceId: z.number().int().positive(),
+  tsMs: z.number().int().min(0),
+  commandType: z.enum(["vibrate", "rotate", "linear", "stop"]),
+  featureIndex: z.number().int().min(0),
+  value: z.number().min(0).max(1),
+  durationMs: z.number().int().positive().optional(),
+});
+
+const bodySchema = z.object({ events: z.array(eventSchema).max(2000) });
+
+export const POST = withRouteLogging(
+  "sessions.events.append",
+  async (req: Request, { params }: { params: Promise<{ id: string }> }) => {
+    const { id } = await params;
+    const parsed = bodySchema.safeParse(await req.json().catch(() => null));
+    if (!parsed.success) {
+      return NextResponse.json({ error: parsed.error.message }, { status: 400 });
+    }
+    await insertEvents(Number(id), parsed.data.events);
+    return NextResponse.json({ inserted: parsed.data.events.length });
+  },
+);