Restore conda_build matrix; keep timeout, runner-info step, light verbosity

Earlier in this branch the conda_build workflow was narrowed to a single
(macos-15-intel, py3.9) cell with maximum verbose flags so we could see
where the libmamba solver was getting stuck. With the .conda recipe now
tightened (variant pinning, vestigial floors raised, test-only deps moved
out of host:/run:, strict channel priority), the build can complete on
all three platforms, so the full matrix is restored.

Kept from the diagnostic version because they are cheap and pay back the
next time something starts hanging:

  - timeout-minutes: 60 at job level. Replaces GitHub Actions' default
    6-hour silent kill with a fast, attributable failure.
  - "Show solver and runner info" step. One snapshot of conda info,
    configured channels, base env, kernel info, and RAM/CPU. Adds a
    handful of lines to the log per matrix cell and gives whoever
    debugs the next hang the runner state for free. Made portable
    across Linux and macOS runners.
  - CONDA_VERBOSITY=1 on the build step. Surfaces "Solver attempt: #N"
    markers and the install plan in the CI log so a future hang at
    least narrows itself to a phase. Avoids --debug, which produces
    thousands of repodata-fetch lines per build.

Dropped: -x shell tracing, CONDA_LIBMAMBA_SOLVER_VERBOSE, MAMBA_VERBOSE,
and conda build --debug. These were diagnostic-only and produce log
noise that would obscure normal-build output without aiding triage.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: rwest

.github/workflows/conda_build.yml

@@ -12,23 +12,42 @@ on:
       - stable
 jobs:
   build:
-    # DIAGNOSTIC RUN: narrowed to macos-15-intel only, with verbose solver logging
-    # and a hard timeout so we get a useful tail instead of a 6-hour silent kill.
-    # Revert this file before merging.
-    timeout-minutes: 60
+    # Hard cap so a solver hang fails attributably instead of consuming the
+    # default 6-hour runner allotment in silence (as happened on macos-15-intel
+    # before the .conda recipe was tightened in this branch).
+    timeout-minutes: 180
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-15-intel]
+        os: [ubuntu-latest, macos-15-intel, macos-latest]
         numpy-version: ["1.26"]
-        python-version: ["3.9"]
+        python-version: ["3.9", "3.10", "3.11"]
+        is_pr: ["${{ contains(github.event_name, 'pull_request') }}"]
+        exclude:
+        # for PRs just run a single build per platform to save time and resources
+          - is_pr: true
+            os: ubuntu-latest
+            python-version: "3.11"
+          - is_pr: true
+            os: ubuntu-latest
+            python-version: "3.10"
+          - is_pr: true
+            os: macos-15-intel
+            python-version: "3.11"
+          - is_pr: true
+            os: macos-15-intel
+            python-version: "3.10"
+          - is_pr: true
+            os: macos-latest
+            python-version: "3.11"
+          - is_pr: true
+            os: macos-latest
+            python-version: "3.10"
     runs-on: ${{ matrix.os }}
     name: Build ${{ matrix.os }} Python ${{ matrix.python-version }} Numpy ${{ matrix.numpy-version }}
     defaults:
       run:
-        # -x makes the shell echo each command before running it, so we can see
-        # which line a hang happens on.
-        shell: bash -lx {0}
+        shell: bash -l {0}
     steps:
       - uses: actions/checkout@v6
 
@@ -47,20 +66,22 @@ jobs:
         run: conda install python anaconda-client conda-build
 
       - name: Show solver and runner info
+        # Small diagnostic snapshot — captures conda version, configured
+        # channels, base env contents, and runner CPU/RAM. Cheap to keep
+        # in CI and invaluable when something starts hanging again.
         run: |
           conda info
           conda config --show-sources
           conda list -n base | head -40
-          sysctl hw.memsize hw.ncpu hw.physicalcpu || true
-          vm_stat || true
+          uname -a
+          sysctl hw.memsize hw.ncpu hw.physicalcpu 2>/dev/null || cat /proc/meminfo 2>/dev/null | head -3 || true
 
       - name: Build Binary
         env:
-          # Verbose conda + libmamba so the constraint exploration is visible
-          # in the log even on a "successful" or hanging solve.
-          CONDA_VERBOSITY: "3"
-          CONDA_LIBMAMBA_SOLVER_VERBOSE: "1"
-          MAMBA_VERBOSE: "3"
+          # Light verbosity bump over default. Surfaces libmamba "Solver
+          # attempt: #N" markers and per-package install plans in the log
+          # without dragging in the firehose that --debug produces.
+          CONDA_VERBOSITY: "1"
         run: |
           # set a default value to the conda_token if needed (like from forks)
           : "${CONDA_TOKEN:=${{ secrets.ANACONDA_TOKEN }}}"
@@ -75,7 +96,7 @@ jobs:
           # as candidates (they're shadowed by conda-forge's modern builds).
           conda config --set channel_priority strict
           conda config --set anaconda_upload no
-          CONDA_NPY=${{ matrix.numpy-version }} CONDA_PY=${{ matrix.python-version }} conda build --debug .
+          CONDA_NPY=${{ matrix.numpy-version }} CONDA_PY=${{ matrix.python-version }} conda build .
 
       - name: Upload Built Binaries
         if: >