fix(build): include shared UI stylesheets in Nx cache inputs (#1360)

* fix(build): include shared UI stylesheets in Nx cache inputs

`libs/ui/styles` held shared SCSS partials but had no `project.json`, so its
files belonged to no Nx project and were absent from every task hash. Editing
a partial and running `pnpm nx build web` reported 4 of 4 tasks cached and
shipped the previous CSS — a silent wrong build rather than a failure.

Nx derives its project graph from TypeScript imports only, so a relative Sass
`@use` that crosses a project root creates no edge. Verified directly: after
adding the project but before declaring anything, `ui-styles` still had zero
dependents in the graph.

Make it the `ui-styles` project (no targets — it exists to be hashed) and
declare `implicitDependencies` on the 8 consumers. Chosen over adding the path
to `sharedGlobals`, which would put shared styles into every project's hash and
make a one-line SCSS tweak mark the whole workspace affected. A styles edit now
marks 15 projects affected and leaves electron-backend, website, the mock
servers and the shared libs alone.

`libs/ui/styles` was the only projectless directory holding files under `libs/`
or `apps/`.

Add `pnpm run styles:inputs:validate` to keep it closed: it resolves every
relative stylesheet import against Nx's real project graph and fails when one
escapes the input closure of a build that compiles it, naming the project to
declare. It exits 1 with 21 diagnostics on the pre-fix tree. Imports of
`apps/web/src/nav-list.scss` are deliberately accepted — `web` already hashes
that file, and a lib -> app edge would make the graph cyclic.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* fix(build): spawn git without a shell in the stylesheet check

`execSync("git ls-files '*.scss'")` runs through `cmd.exe` on Windows, where
single quotes are literal characters rather than quoting. Git received the
pathspec with the quotes intact, matched nothing and exited 0, so
`styles:inputs:validate` reported success after checking zero stylesheets —
silently disabling the check for Windows developers while staying green.

Spawn with `execFileSync` so no shell is involved and git expands its own
pathspec; verified to return the identical 133 files.

Both this and the eslint glob trap next to it in the docs report success while
covering nothing, so also make an empty scan fail rather than pass: the
workspace always contains SCSS, and a listing that returns none means the scan
broke.

Reported by Codex review on #1360.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* refactor(styles): move nav-list partial into ui-styles (#1361)

* fix(build): count every target of a comma-separated Sass @import

`@import` is the only rule that takes a list, and the scan read just its
first target. A later entry crossing an Nx project boundary escaped the
cache key while the check still reported success — the same silent-pass
failure the tool exists to prevent.

Parse every target of an `@import` list. The obvious "read all quoted
strings" fix trades one silent gap for a phantom one, so the rule decides:
`@use`/`@forward` load exactly one module and a quoted string after it is
`with (...)` configuration, and `url(...)` stays a plain CSS import the
browser resolves at runtime. Neither is a module Sass compiles.

The workspace has no relative `@import` at all today, so the scan still
finds the same 42 imports across 133 files; this closes the gap before
someone writes one.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

AGENTS.md

@@ -18,6 +18,13 @@ This file provides guidance to coding agents working in this repository.
 - See `docs/architecture/nx-workspace-boundaries.md` for the current Nx tag and alias policy.
 - Keep `nx` and every official `@nx/*` package on the same exact version; run
   `pnpm run deps:nx:validate` after dependency updates.
+- A directory holding files consumed by other projects must be an Nx project.
+  Nx builds its graph from TypeScript imports only, so a relative SCSS `@use`
+  across project roots creates no edge and the imported file lands in no task
+  hash — edits then return a cache hit instead of rebuilding. Shared partials
+  live in `libs/ui/styles` (project `ui-styles`), and each consumer declares
+  `"implicitDependencies": ["ui-styles"]`. Run `pnpm run styles:inputs:validate`
+  after adding a cross-project stylesheet import.
 - Update Nx with `pnpm nx migrate nx@<target> --skipInstall`, regenerate the
   lockfile, run generated migrations when present, and validate before opening
   a PR. Major updates are always manual. Replace incomplete Dependabot security