Add 32-bit CI lane via test_groups.toml (stacked on #97) (#98)

* Add generic findfirstsortedequal fallback (fixes 32-bit) and drop the broken 32-bit CI job

Follow-up to #95. Two things:

1. Fix a correctness gap #95 shipped. Unlike `findfirstequal`,
   `findfirstsortedequal` had ONLY the `(Int64, DenseVector{Int64})` method
   and no generic fallback. On 32-bit platforms native `Int` is `Int32`, so
   `findfirstsortedequal(::Int32, ::Vector{Int32})` throws MethodError — 8385
   such errors in the suite, and a bare `Pkg.test()` / any `Int`-vector caller
   on 32-bit is broken. Add a generic `searchsortedfirst` + equality post-check
   fallback (mirroring `findfirstequal`), so it works for any sorted vector on
   any platform. Add a test covering the fallback on Int32/Int16/Float32.

2. Remove the `tests-32bit` job #95 added to Tests.yml. Running 32-bit Julia on
   the 64-bit `ubuntu-latest` runner fails at `setup-julia` (the i686 binary
   can't exec without the 32-bit loader, which is not installed before Julia is
   invoked: `spawn .../x86/bin/julia ENOENT`), so that job is red regardless of
   this fix. A proper 32-bit CI lane needs runner/reusable-workflow changes and
   is deferred; Tests.yml goes back to a thin grouped-tests caller.

Minor bump 3.0.3 -> 3.1.0 (new public behavior: `findfirstsortedequal` now
accepts any sorted vector). Verified locally: full Core suite passes on 32-bit
i686 Julia 1.11 (0 errors) and on x64 (171915 tests); GROUP=All passes.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EcQkauMQ4KSytnTpJpXUZu

* Add the 32-bit CI lane via test_groups.toml

Declare a `Core 32-bit` matrix-only alias that dispatches the Core body
(group = "Core") on a single x86 Julia cell, so the WORD_SIZE != 64 scalar
fallbacks in src/simd_ir.jl are exercised in CI — replacing #95's hand-added
`tests-32bit` job (removed in the parent commit) with a declarative lane.

This uses the arch axis / group alias in SciML/.github v1 (v1.24.0) and the
i386 runtime-lib install before setup-julia (v1.24.1), so the x86 leg can
actually run on the 64-bit ubuntu runner.

Require `SciMLTesting = "2.2"`: the alias section is skipped by folder discovery
only in SciMLTesting >= 2.2 (SciMLTesting.jl#22), which GROUP=All (the Downgrade
job) and a bare `Pkg.test()` need. FindFirstFunctions runs unchanged on
SciMLTesting 2.x (verified: Core suite passes on 2.1.0).

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EcQkauMQ4KSytnTpJpXUZu

---------

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

Project.toml

@@ -9,7 +9,7 @@ PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
 [compat]
 PrecompileTools = "1.0.1"
 SafeTestsets = "0.1"
-SciMLTesting = "1"
+SciMLTesting = "2.2"
 StableRNGs = "1"
 Test = "1.10"
 julia = "1.10"

test/test_groups.toml

@@ -6,5 +6,15 @@
 versions = ["1", "lts", "pre"]
 os = ["ubuntu-latest", "macos-latest", "windows-latest"]
 
+# 32-bit lane: a matrix-only alias that dispatches the Core body (GROUP=Core) on
+# a single x86 Julia, so the WORD_SIZE != 64 scalar fallbacks in src/simd_ir.jl
+# are exercised in CI. The `arch = "x86"` cell needs SciML/.github v1's i386-libs
+# step (setup-julia) and the alias skip in SciMLTesting >= 2.2 (folder discovery).
+["Core 32-bit"]
+group = "Core"
+versions = ["1"]
+os = ["ubuntu-latest"]
+arch = "x86"
+
 [QA]
 versions = ["lts", "1"]