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>

components/layout/Breadcrumbs.tsx

@@ -6,7 +6,6 @@ import { ChevronRight, House } from "lucide-react";
 
 const SECTION_LABELS: Record<string, string> = {
   control: "Control",
-  recordings: "Recordings",
   sessions: "Sessions",
   stats: "Stats",
   devices: "Devices",

components/layout/NavBar.tsx

@@ -14,7 +14,6 @@ import { cn } from "@/lib/utils";
 const LINKS = [
   { href: "/", label: "Dashboard" },
   { href: "/control", label: "Control" },
-  { href: "/recordings", label: "Recordings" },
   { href: "/sessions", label: "Sessions" },
   { href: "/stats", label: "Stats" },
   { href: "/devices", label: "Devices" },