fix: correct interleaved streaming order (Text → Thinking → Tool → Text) (#913)

* fix: correct interleaved streaming order (Text → Thinking → Tool → Text)

During live streaming, tool cards were inserted before their associated
thinking cards instead of after them. The root cause was that
appendLiveToolCard's anchor selector didn't include .thinking-card-row,
so finalized thinking cards were skipped when finding the insertion point.

Changes:
- messages.js: Add segment splitting (segmentStart/_freshSegment) so each
  text segment after a tool call renders only its own slice, not the full
  accumulated text. Sync thinking card render in reasoning handler to
  avoid rAF race with tool events. Guard removeThinking() to preserve
  finalized cards when reasoningText is active.
- ui.js: Add .thinking-card-row to appendLiveToolCard anchor selector so
  tool cards land after finalized thinking. Add anchor-based positioning
  to appendThinking for correct interleaved placement. Clean up empty
  spinner-only thinking rows in finalizeThinkingCard. Add 3-dot waiting
  indicator (toolRunningRow) after tool cards for visual feedback.
- style.css: Scope blinking cursor to last live-assistant segment only.
  Add spacing for toolRunningRow.

* chore: CHANGELOG for v0.50.174

---------

Co-authored-by: bsgdigital <bsgdigital@users.noreply.github.com>
Co-authored-by: nesquena-hermes <nesquena-hermes@users.noreply.github.com>

CHANGELOG.md

@@ -29,6 +29,11 @@
   workspace subtree) and never enumerate blocked system roots. (`api/routes.py`,
   `api/workspace.py`, `static/panels.js`, `static/style.css`) (partial for #616)
 
+## [v0.50.174] — 2026-04-23
+
+### Fixed
+- **Interleaved streaming order (Text → Thinking → Tool → Text)** — after a tool call completes, new text tokens now create a new DOM segment below the tool card instead of updating the old segment above it. Adds `segmentStart`/`_freshSegment` flags to track segment boundaries; scopes the streaming cursor to the last live assistant segment only; adds a 3-dot waiting indicator below each tool card; fixes `appendLiveToolCard`/`appendThinking` anchor logic for multi-tool sequences. (`static/messages.js`, `static/ui.js`, `static/style.css`) Co-authored by @bsgdigital.
+
 ## [v0.50.173] — 2026-04-23
 
 ### Fixed