Voiden: allar útgáfur og eldri útgáfur

## Cursor Dark Default Theme & Editor Reliability

Patch release switching the default theme to Cursor Dark, plus fixes for markdown preview
correctness/performance, theme-broken popovers, and a set of app-wide Zustand re-render leaks that
made large files sluggish.

### Improved

- Cursor Dark is now the default theme for new installs and after Reset Settings, instead of the
original Voiden theme — existing installs keep whatever theme they've already picked
- Split/preview markdown popups (pre/post-request script help, table header help) are now capped at
50% of the window height with internal scrolling instead of being able to overflow past the bottom
of the screen

### Fixed

- Switching tabs quickly could briefly show the previous tab's content — and, if it was a markdown
file, the previous tab's rendered preview — under the newly active tab's title, due to a stale-tab
race in the tab-content loading hook
- Onboarding modal used hardcoded hex colors and Tailwind default-palette classes instead of theme
tokens, so it looked wrong (and had an undefined CSS variable border) in every non-default theme
- Markdown preview no longer freezes the whole window when opening a large file — it previously
re-parsed the entire document synchronously on first render with no size limit; large files now
show an opt-in "file is large" banner instead of auto-rendering, and typing/scrolling in the
preview no longer blocks on every keystroke
- Inline code inside a numbered or bulleted list item no longer corrupts the whole document into
raw YAML block syntax after saving and reopening — a serializer fallback meant for top-level blocks
was also triggering for list-nested paragraphs, dumping their content as a ---\ntype: paragraph...
block instead of normal markdown (#493)

### What's Changed

- fix: preserve unresolved shell env vars during curl import instead of… by @rajarshi1 in #499
- Revert "fix: preserve unresolved shell env vars during curl import instead of…" by @phurpa-tsering
in #504
- Beta to main by @phurpa-tsering in #505
- Beta to main merge by @phurpa-tsering in #506
- Beta to main by @phurpa-tsering in #507

### New Contributors

- @rajarshi1 made their first contribution in #499