v0.7.1: Streaming + Markdown + URLs + Interrupt — TDD

Stream-chunk protocol: SSE streaming via provider-openai-stream,
cascade-stream with fboundp guard in think(). TUI renders live.

Stream interrupt: Esc during streaming marks [interrupted], finalizes msg.
SSE cancel infrastructure: *stream-cancel* check in read loop.

Markdown inline: **bold**, *italic*, `code` via parse-markdown-spans.
Code blocks: parse-markdown-blocks + syntax-highlight (keywords/strings/fns).
URL detection + Tab-to-activate: https:// URLs in dim, Tab opens.

Watchdog: 30s stall detection via Dexador read-timeout.
[streaming] indicator in status bar.

Pre-existing TUI test fixes (7): first→aref, nil→zerop, add-msg arg.

Core: 65/65  Neuro: 13/13  TUI View: 22/22  TUI Main: 65/65
Total: 165 tests, 0 failures.

org/channel-tui-state.org

@@ -134,6 +134,7 @@ See *tui-theme-presets* for named presets (dark, light, solarized, gruvbox).")
               :scroll-offset 0 :busy nil :cursor-pos 0
               :pending-ctrl-x nil
               :scroll-at-bottom t :scroll-notify nil
+              :streaming-text nil :url-buffer nil   ; v0.7.1
               :dirty (list nil nil nil))))
 #+end_src