v0.8.2

Added

• Plugins can send media through ctx.conversations.send. The conversation-send capability now accepts image, video, audio, and file envelopes that carry a mediaUrl, sending them by URL through the same media pipeline as the REST media endpoints (the caption comes from text). It stays under the existing conversation:send permission and the plugin's activated-session scope — the text/reply behavior is unchanged. A replyTo on a media envelope is rejected, since the engine media path cannot quote a message.
• Official Java SDK (com.rmyndharis:openwa). A hand-written, synchronous Java 17 client covering the full REST surface — all 12 resources (sessions, messages, contacts, groups, webhooks, chats, labels, channels, catalog, status, templates, health) plus API-key validation — with typed request builders, immutable response records, a typed error hierarchy, and an injectable HTTP transport for testing. One runtime dependency (Gson); published to Maven Central as com.rmyndharis:openwa:0.1.1. Lives in sdk/java and is drift-tested against the backend DTOs like the JavaScript, Python, and PHP SDKs. (#602)