Code fences with /path:start-end on the fence line get parsed.
Apply replaces that line range in the target file.
Fallback: insert at cursor or replace selection.
agent-copilot.md instructs model to produce ranged fences.
Context menu: right-click selection shows Fix/Refactor/Add tests/Document
actions that submit the selection with file+line context to the agent.
Apply button: code blocks in assistant messages get a clickable Apply
button that inserts the code into the target file (detected from
preceding prose) or the active document.
Inline annotations: file:line references in agent output are highlighted
with MovingRanges in the active editor view.
setHtml() resets the document layout. sb->setValue(sb->maximum()) was
reading a stale maximum before relayout completed. Use moveCursor(End)
+ ensureCursorVisible() which forces layout and scrolls reliably.
Also: fix session list state updates destroying delegates (rename fix)
already included in previous commit.