fix(#3673): docs site bug sweep - push drawer filters, side menu, multi-sort, responsive grids

[twjeffery]

Closes #3673

Summary

Hands-on walkthrough of the docs site to find and fix accumulated issues after recent PRs landing (config examples, preview images, app header V2, push drawer, get started pages).

Side menu

• Removed stale useGroupShadowDomFixes shadow DOM workaround. After feat: make icon optional in WorkSideMenuGroup and WorkSideMenuItem #3595 made icons optional, the workaround was hiding the chevron instead of the (now absent) leading icon.
• Added missing onNavigate handler on Foundations sub-menu.

Push drawer filters (Examples, Components, Tokens)

• Replaced overlay GoabxDrawer with GoabxPushDrawer on all three grid pages
• Push drawer portaled outside the content card at the layout level so it pushes the card over
• Negative margins on the portal cancel layout padding, letting the drawer's built-in offset handle spacing
• --card-padding-h CSS variable keeps sticky toolbar width in sync across breakpoints
• Filter button toggles drawer open/closed
• At <1024px the push drawer falls back to modal overlay with proper z-index handling
• Mobile header z-index drops when drawer is open using :has([open])

Responsive grids

• Card grids changed from fixed repeat(4, 1fr) to auto-fill with minmax(200px, 1fr)
• Service pattern cards use auto-fit with minmax(250px, 1fr)
• Tokens toolbar stacking uses @container query instead of @media

Multi-sort tables

• Enabled sort-mode="multi" on all three goa-table instances (using feat(#3344): add multi-column sorting to Table and TableSortHeader #3409)
• Switched from _sort to _multisort event handling
• Added sort-order attribute for visual "1"/"2" badges
• Removed sort chips (redundant with header indicators), kept filter/search chips

Homepage

• "Public form" links to /examples/public-form instead of /examples?userType=citizen
• "Workspace" links to /examples/workspace instead of /examples?userType=worker

Sticky toolbar

• ::before constrained to content card padding (was left/right: -9999px)
• Removed extra bottom margin when sticky
• View toggle wrapper clipped to 40px

Mobile header

• Title: body-s with greyscale-700 (was mobile-heading-xs)
• Gap adjustments between menu button, logo, and title
• Removed negative margins on icon buttons (16px from screen edge)

Other

• Support page button changed to compact
• Component card thumbnail margin reduced from space-xs to space-2xs

Test plan

• Side menu: chevrons visible on category groups, all sub-menu items clickable
• Push drawer: opens/closes on filter button, pushes content card, grid reflows
• Push drawer <1024px: falls back to modal overlay, scrim covers mobile header
• Push drawer mobile: modal drawer works, layout not broken
• Multi-sort: click two columns, both show sort arrows with 1/2 badges
• Homepage: service pattern cards link to correct pages
• Sticky toolbar: constrained to content card width at all breakpoints
• Mobile header: correct typography, spacing, icon button padding