fix(ui): replace icon ligatures missing from the font and guard them (#1864)

* fix(ui): replace icon ligatures missing from the font and guard them

The download and recording queues showed the literal text "file_off" for a
missing file: the bundled Material Icons font (material-design-icons-iconfont
6.7.0) has no such ligature, so it rendered as text overflowing the icon box.
Use error_outline, which the missing state's tertiary palette keeps distinct
from the filled error glyph of a failed download.

Add `pnpm run styles:icon-ligatures:validate` (CI): it parses templates with
@angular/compiler and TypeScript with the compiler API, collects static
<mat-icon> text, the string results of its bindings, icon/*Icon inputs and
icon-named TypeScript values, and fails on a name missing from the font's
codepoints file. Two listed codepoints the font has no ligature for
(rounded_corner, stairs) are excluded.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(tools): check quoted inline templates in the icon guard

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(tools): accept every codepoint and report escaped template lines

The first measurement rendered the names without the package's CSS. With
material-design-icons.css, all 2,193 codepoint names, rounded_corner and
stairs included, draw as one glyph, so the guard accepts the whole file.

Inline templates now map each cooked position back to the source through
escapes, line continuations and CRLF, so a name after `\n` in a quoted
template is reported on the line it is written on.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -409,6 +409,10 @@ jobs:
             - name: Validate Angular Material token overrides
               run: pnpm run styles:material-tokens:validate
 
+            # The icon font renders an unknown ligature name as plain text.
+            - name: Validate Material icon names
+              run: pnpm run styles:icon-ligatures:validate
+
             # Nx rejects a non-parallel task with continuous dependencies, and
             # the Playwright plugin infers serve dependencies only when CI is
             # unset, so this checks both the local and the CI inference.