fix(spur-cli): honor SPUR_* env-var twins in sbatch (#526)

sbatch resolved env defaults through clap's `env` attribute, which takes a
single variable name per flag, so the SPUR_* twins that srun and salloc
accept were silently ignored. Route sbatch through the shared env_defaults
resolver instead, applying env after the directive merge and only to flags
the CLI did not set, which preserves the CLI > env > #SBATCH precedence.

SPUR_JOB_NAME and SPUR_NODELIST stay unread: both are injected into every
running job, so honoring them would make an sbatch submitted from inside a
job inherit the enclosing job's name and node placement.

Co-authored-by: harssriv <harssriv@amd.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

Author: 3 people

crates/spur-cli/src/env_defaults.rs

@@ -1,7 +1,7 @@
 // Copyright (c) 2026 Advanced Micro Devices, Inc. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-//! Environment-variable defaults for `srun` and `salloc` flags.
+//! Environment-variable defaults for `srun`, `salloc`, and `sbatch` flags.
 //!
 //! clap's `#[arg(env = ...)]` accepts a single variable name, but Slurm
 //! defines several aliases per flag (e.g. `--nodes` reads `SLURM_NNODES` and
@@ -169,10 +169,10 @@ where
 
 /// Test-only guard that isolates env-var tests from the runner's environment.
 ///
-/// Clears every `SPUR_/SLURM_/SALLOC_/SRUN_`-prefixed variable on construction
-/// and on drop, so a CI runner that injects `SLURM_*` vars cannot perturb the
-/// resolvers and a panicking test cannot leak state into the next one. Tests
-/// using it must be `#[serial]`.
+/// Clears every `SPUR_/SLURM_/SALLOC_/SRUN_/SBATCH_`-prefixed variable on
+/// construction and on drop, so a CI runner that injects `SLURM_*` vars cannot
+/// perturb the resolvers and a panicking test cannot leak state into the next
+/// one. Tests using it must be `#[serial]`.
 #[cfg(test)]
 pub(crate) struct EnvGuard;
 
@@ -195,6 +195,7 @@ impl EnvGuard {
                     || k.starts_with("SLURM_")
                     || k.starts_with("SALLOC_")
                     || k.starts_with("SRUN_")
+                    || k.starts_with("SBATCH_")
             })
             .collect();
         for k in stale {