chore(frontend): drop unused autoprefixer dep

[nabramovitz]

Closes the loop on #5933, which proposed bumping autoprefixer 10.5.5 to 10.6.0. The dependency is unused, so it is removed rather than bumped.

Why it is dead

autoprefixer is a root devDependency that nothing resolves:

• postcss.config.json registers only @tailwindcss/postcss.
• The app builds through @angular-devkit/build-angular:application, which delegates to @angular/build — a package with no autoprefixer reference at all. ng-packagr has none either.
• The only require('autoprefixer') in the tree sits in @angular-devkit/build-angular/src/tools/webpack/configs/styles.js, the legacy webpack path, which this project does not use.
• Vendor prefixing now comes from esbuild, whose target @angular/build derives from the browserslist file via src/tools/esbuild/target.js.

How it got here

The Tailwind v4 migration in 81f7622 removed autoprefixer from the PostCSS plugin list, with a comment recording why:

// Tailwind v4 PostCSS pipeline.
// v4 has native CSS Nesting and Lightning-CSS-based vendor prefixing,
// so the v3 helpers (tailwindcss/nesting + autoprefixer) are gone.

That commit added @tailwindcss/postcss to the manifest but did not remove the entry it replaced. The config migrated; the dependency list did not.

Verification

Built develop and this branch and compared the emitted stylesheet:

before (autoprefixer 10.5.5 installed): 157252 bytes  md5 32b982cc15745772d594537f14bcd9da
after  (dependency removed)           : 157252 bytes  md5 32b982cc15745772d594537f14bcd9da

Byte-identical, 30 -webkit- prefixes either way, and the one hand-written -webkit-line-clamp rule is unchanged. Both builds exit 0 with 0 errors.

Also in this PR

Removing the direct dependency collapses a duplicate resolution — autoprefixer now appears once, as build tooling's own transitive dep at 10.5.4, instead of twice at 10.5.4 and 10.5.5.

Two references the v4 migration left stranded are cleaned up: the packages/core/browserslist header naming autoprefixer as its reader, and an autoprefixer: ignore next directive nothing reads any more. The hand-written -webkit- properties it guarded are untouched.

Second commit: the dead Firefox fade block

Unrelated to autoprefixer, but in the same file, so it rides along as its own commit.

98ec379 commented out a Firefox-only fade overlay in 2019 rather than deleting it, marking it "no longer fit for purpose". It was a workaround for Firefox lacking multi-line text ellipsis, and it applied unconditionally — single-line titles got a fade that cut them off (#3544).

The premise expired three months later: Firefox 68 shipped -webkit-line-clamp in July 2019, so Firefox clamps through the same rule as every other target. The browserslist entries are Firefox ESR and last 2 versions, both well past 68.

That left twenty lines of commented-out CSS whose opening line states something untrue. The rationale stays in the commit history and in the linked issue.

Sass strips // comments before they reach CSS, so this cannot affect output — and the byte-identical check above was re-run with this commit applied, still matching develop exactly.

[norman-abramovitz]

LGTM for the latest change