Add "All dashboards" print-friendly stacked view (ticket 009)

Adds an "All dashboards" selector alongside the existing click-to-select
single-dashboard view. Selecting it stacks every dashboard vertically in
normal document flow, each preceded by a heading naming it, with no
fixed-height or scroll-clipping containers, so the browser's native print
function can render the full stack across pages.

Verified in-browser: single-dashboard editing still works unchanged, and
"All dashboards" renders all dashboards (including an empty one) stacked
with named separators; confirmed via computed layout that only the
pre-existing app-level scroll container grows to fit the content, with no
clipping container inside the Dashboards section itself.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o

tickets/009-all-dashboards-print-friendly-view.md

@@ -1,9 +0,0 @@
-# Add "All dashboards" option with print-friendly stacked layout
-
-The dashboards part should keep the click-to-select dashboards, however it should have an "All dashboards" option. In that situation, the dashboards are displayed one after another with named separators. This is important so that it is possible to print the page or print the dashboards section. Printing itself is a browser capability we don't need to implement, but the page should be laid out in a way that's compatible with it.
-
-## Acceptance criteria
-- Existing click-to-select single-dashboard view is preserved.
-- New "All dashboards" option stacks all dashboards vertically, one after another, each preceded by a named separator (dashboard name/title).
-- The stacked layout uses normal document flow (no fixed-height scroll containers that would clip content) so the browser's native print function can render the full stacked content across pages.
-- Verified visually in browser, including a print-preview check.