ui: the sidebar's tabs become one dock; Measure and Signals by keyboard section; session keeps the dock's state

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/claude/architecture.md

@@ -36,7 +36,7 @@ What feeds `Acquisition` is a `DataSource`, one of the registered *kinds*.
   `src/source/udps_*.cpp` (`grep -rn "udps_" src` outside those files is a leak of the old coupling).
 - The frame is **single-timebase**. A multi-timebase source (ABScope) will change the interface and
   the data path together; do not bend one frame to carry two clocks.
-- A kind's capability panels are pages of `side_stack`, named `source-<id>`. A disconnected source
+- A kind's capability panels are pages of the slide-over (`slideover_add_page`), named `source-<id>`. A disconnected source
   leaves them **insensitive, not hidden** (`apply_source_panels` in `src/ui_source.cpp`).
 - Session file naming for a non-UDPS kind: the pseudo-host is `<kind>-<identity>` (characters outside
   `[A-Za-z0-9._-]` become `_`) on port **1** (0 is rejected by the session-file parser), the kind is