feat: LLM streaming with UX improvements

[Jurij89]

Summary

• SSE streaming
  Server-sent events transport for real-time LLM responses on web (native path unchanged).
  Includes server-side processStreamingCompletion with .stream() → .invoke() fallback, client-side SSE parser, and rAF-throttled UI updates.

• Plain text during streaming
  Renders raw <Text> instead of Markdown while tokens arrive, eliminating visual glitches from incomplete markup (unclosed fences, bold, partial links).
  Switches to full Markdown on completion.

• Code block copy button
  Fenced code blocks display a copy icon (top-right) that swaps to ✓ Copied feedback for 2 seconds.

• Scroll UX
  No auto-scroll during streaming or on completion (matches Claude/ChatGPT behavior).
  Scrolls to bottom only when the user sends a new message.

Files changed

File	What
apps/agent/src/shared/chat.ts	SSE types, processStreamingCompletion (server), makeStreamingCompletionRequest (client), writeSSE helper
apps/agent/src/server/index.ts	Streaming middleware plugin (intercepts Accept: text/event-stream on /llm)
apps/agent/src/app/(protected)/chat.tsx	streamingContent state, streaming functions, plain text rendering, scroll-on-send
apps/agent/src/components/Markdown.tsx	CopyCodeButton component, custom fence render rule

Test plan

• Send a message on web — verify tokens stream in real-time with plain text
• Verify final message renders with full Markdown (bold, code blocks, lists)
• Verify no auto-scroll during streaming — user can read at their own pace
• Verify sending a new message scrolls to bottom
• Verify code block copy button copies content and shows ✓ Copied feedback
• Verify native (non-streaming) path is unaffected
• Verify tool calls work correctly through the streaming path

[Bojan131]

Tested and some markdown parts seem not to be working. Bolded text and code blocks dont seem to be visible. When you ask it to put it in a code block it does do it but it doesn't put it automatically and also it has a delay where it puts it in a code block when the whole message stops streaming instead of streaming the code into the code block

Please take a look at the image attached.
Other things work as expected