build(deps): bump postcss and styled-components in /rest-gateway

[dependabot]

Removes postcss. It's no longer used after updating ancestor dependency styled-components. These dependencies need to be updated together.

Removes postcss

Updates styled-components from 6.1.19 to 6.4.1

Release notes

Sourced from styled-components's releases.

styled-components@6.4.1

Patch Changes

• 49d09ae: Fix a performance regression in 6.4.0 where dynamic createGlobalStyle components caused significant re-render slowdowns. Also restores pre-6.4 cascade ordering when multiple instances of the same createGlobalStyle coexist.
• eca95b2: Fix outdated dev-mode error messages for keyframes-in-untagged-strings and component-selector references that still pointed at www.styled-components.com and described behavior from styled-components v3.

styled-components@6.4.1-prerelease-20260417184545

Full Changelog: https://github.com/styled-components/styled-components/compare/styled-components@6.4.1-prerelease-20260417184031...styled-components@6.4.1-prerelease-20260417184545

styled-components@6.4.1-prerelease-20260417184031

What's Changed

• fix: avoid double rebuildGroup on every dynamic createGlobalStyle render (#5730) by @​quantizor in styled-components/styled-components#5732

Full Changelog: https://github.com/styled-components/styled-components/compare/styled-components@6.4.0...styled-components@6.4.1-prerelease-20260417184031

styled-components@6.4.0

Minor Changes

• b0f3d29: .attrs() improvements: props supplied via attrs are now automatically made optional on the resulting component (previously required even when attrs provided a default). Also fixes a bug where the attrs callback received a mutable props object that could be changed by subsequent attrs processing; it now receives an immutable snapshot.

• 2a973d8: Dropped IE11 support: ES2015 build target, inlined unitless CSS properties (removing @​emotion/unitless dependency), removed legacy React class statics from hoist and other unnecessary code.

• 9e07d95: Add createTheme(defaultTheme, options?) for CSS variable theming that works across RSC and client components.

  Returns an object with the same shape where every leaf is var(--prefix-path, fallback). Pass it to ThemeProvider for stable class name hashes across themes (no hydration mismatch on light/dark switch).

  const theme = createTheme({ colors: { primary: '#0070f3' } });
  // theme.colors.primary → "var(--sc-colors-primary, #0070f3)"
  // theme.raw → original object
  // theme.vars.colors.primary → "--sc-colors-primary"
  // theme.resolve(el?) → computed values from DOM (client-only)
  // theme.GlobalStyle → component that emits CSS var declarations

  vars exposes bare CSS custom property names (same shape as the theme) for use in createGlobalStyle dark mode overrides without hand-writing variable names:

  const { vars } = createTheme({ colors: { bg: '#fff', text: '[#000](https://github.com/styled-components/styled-components/issues/000)' } });
  const DarkOverrides = createGlobalStyle@media (prefers-color-scheme: dark) { :root { ${vars.colors.bg}: [#111](https://github.com/styled-components/styled-components/issues/111); ${vars.colors.text}: #eee; } };

... (truncated)

Commits

• 37a0a5e Version Packages
• 2f1a3fb ci: per-package prerelease notes with progression link [skip ci]
• fea4919 ci: match prerelease notes to release job format [skip ci]
• e557e11 style: align prerelease job formatting with release job
• a3dee6d ci: collapse prerelease workflow into release.yml
• 52bda0c chore: add husky pre-commit hook running prettier
• eca95b2 chore: add changeset for stale error message fix
• c8db03c fix(build): emit errors.ts from generator so compiled bundle matches errors.md
• 45e4b84 docs(agents): drop duplicated Float and new Array rules
• 368fb93 docs: drop v3/v4 history from keyframes untagged-string error
• Additional commits viewable in compare view

Maintainer changes

This version was pushed to npm by GitHub Actions, a new releaser for styled-components since your current version.

[wajda]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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[wajda]

@dependabot rebase

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud