Design System: New Fluent theme (dxdsfluent) powered by design tokens, fix hardcoded colors in Widget Gallery - #34698

…mos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in Overview,
CurrentTimeIndicator, Timelines, Templates. Fallback preserves the exact
legacy value, so existing themes are visually unaffected; fluent-next
resolves the token.

…os (WG)

Replaces hardcoded colors with var(--dxds-*, original) in Row,
Row3RdPartyEngineTemplate, RemoteCRUDOperations. Fallback preserves the
exact legacy value. Colors still marked unresolved by designers (#000,
#484848, DevExpress#777 in Row's dark-mode hover rules) are left untouched.

…(WG)

Replaces hardcoded colors with var(--dxds-*, original) in TaskTemplate
(6 of 7 custom task colors, both #fff occurrences) and StripLines.
Fallback preserves the exact legacy value. #7B1FA2 stays untouched
(still unresolved by designers).

…os (WG)

Replaces hardcoded colors with var(--dxds-*, original) in ItemTemplate
and Item3RdPartyEngineTemplate. Fallback preserves the exact legacy value.

… (WG)

Replaces hardcoded colors with var(--dxds-*, original) in
PopupAndNotificationsOverview (#f05b41 across all 6 occurrences,
#ff6a50, #fff) and FormsOverview (#d2d3d5). Fallback preserves the
exact legacy value. rgba(19, 32, 51, 0.8) and rgba(255, 255, 255, 0.4)
stay untouched (still unresolved by designers).

…x and TabPanel demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in
ResponsiveBox/Overview (5 panel colors + text color) and
TabPanel/Overview (3 priority colors + dark-mode background). Fallback
preserves the exact legacy value. #fff and rgba(0, 0, 0, 0.15) in
TabPanel stay untouched (still unresolved by designers).

…FileUploader demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in
CustomShapesWithTemplates(+WithEditing), CustomDropzone, FileSelection.
Fallback preserves the exact legacy value.

… Toolbar demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in Sortable/Kanban
(3 priority colors, #86c285 across both occurrences) and
Toolbar/Adaptability (DevExpress#999, #ddd across both occurrences, #fff).
Fallback preserves the exact legacy value. #adadad and the rgba(...)
boilerplate/shadow colors stay untouched (still unresolved by designers).

…ProgressBar and Gauges demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in
RadioGroup/Overview (gray/green/orange/red priority dots),
ProgressBar/Overview (green complete state), and Gauges/Overview
(#f05b41 across all 4 CSS occurrences, #fff). Fallback preserves the
exact legacy value. The #f05b41 JS widget-config color (needle/scale,
set via JS API rather than CSS) is out of scope and left untouched.

…r, LoadPanel and MultiView demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in Box/Overview,
Calendar/Overview, LoadPanel/Overview (both border occurrences),
MultiView/Overview (both border occurrences). Fallback preserves the
exact legacy value. Note: Calendar/Overview's .weekend color rule is
already overridden by higher-specificity theme CSS in both the legacy
and new theme (pre-existing, unrelated to this change).

…Streaming demo (WG)

Replaces hardcoded colors with var(--dxds-*, original) per the exact
selector/property mapping from plan.md §2.2.1: chat-suggestion-card
border/background (rest + hover), card title and prompt text colors.
Fallback preserves the exact legacy value (uppercase hex, as in
source). rgba(0, 0, 0, 0.02/0.04) box-shadow colors stay untouched
(still unresolved by designers).

… Form and Pagination demos (WG)

Replaces hardcoded colors with var(--dxds-*, original) in
ButtonGroup/Overview (#ddd), Form/ItemCustomization (#42a5f5),
Pagination/Overview (#fff). Fallback preserves the exact legacy value.
Completes Phase A of the hardcoded-colors task (39 demos, 84 colors).