fix(boundary): detect item-type arrays anywhere in src/ (DR-094)

check:boundary passed on the very leak it was written for. The pattern was
anchored to `includeItemTypes:` at the query site, so searchScope.ts
assigning the same array to a named const and dereferencing it one
indirection away was invisible — through every green CI run.

The check now matches an array literal naming two or more Jellyfin item
types anywhere in src/, catching a const, a Record value, a function
return, and an inline query alike. Deliberate limits kept: two adjacent
literals required (single-type presentation stays legal), string literals
required (item.type === "Audio" is display logic), explicit type list
(so ["High","Low"] produces no noise).

Verified all five cases: reintroducing the original SCOPE_ITEM_TYPES
fails; a new const ["Movie","Series"] fails; the same array in a
.test.ts passes; itemType: "Movie" / item.type === / ["High","Low"] pass;
a 5th allowlist entry fails on the new cap.

Allowlist 1→3 entries, capped at 4 so the next exception forces a
conversation rather than a one-line append:
- GenericMediaListPage: grid styling over a self-declared itemType —
  presentation, changes only with a UI redesign.
- DownloadedBrowse: borderline, leans domain (the container set grows
  when Jellyfin adds a container type). Allowlisted with a TODO for a
  backend MediaItem.isContainer flag.

The header now names what the check still cannot see — run-time-built
sets, types split across variables, switch/|| taxonomy — and CLAUDE.md
states that a green check:boundary is not proof. That matters given this
check passed on its own founding violation for months.

Also: both gates wired into test-all.sh, which called `bun run test`
without --run and would have hung in watch mode. Corrected the Dockerfile
comment describing the Windows toolchain as mingw/GNU — it is MSVC via
cargo-xwin (GNU cannot bundle NSIS from Linux).

CLAUDE.md

@@ -183,8 +183,14 @@ and [docs/build-release.md](docs/build-release.md).
   backend expand it. Single-type presentation (`itemType: "Movie"`, "this page
   shows albums") is fine; a *category → set of types* mapping in `src/` is a leak.
   `bun run check:boundary` is the tripwire; the real gate is the spec's layer
-  assignment. See [scoped-search-boundary.md](docs/specs/scoped-search-boundary.md)
-  for the incident this rule came from.
+  assignment. The canonical example lives in Rust:
+  `SearchScope::item_types()` in `repository/types.rs` expands an opaque scope the
+  frontend sends. See [scoped-search-boundary.md](docs/specs/scoped-search-boundary.md)
+  for the incident this rule came from — note the tripwire missed that leak for
+  months because the mapping was assigned to a named const rather than written
+  inline at the query, so **a green `check:boundary` is not proof**; it flags
+  item-type array literals only, not run-time-built sets or `switch`/`||`
+  taxonomy.
 
 ## Writing specs