Add Azurite test support for AzureBlobStore

[Muktarsadiq]

What and why

Adds Azurite (Azure Storage emulator) support to the test suite for
AzureBlobStore, so it's exercised against a real emulator rather than
only mocks. Follows the existing mongo_runner embedded-runner pattern.

Fixes #2511

How was this verified?

Ran cargo test -p nativelink-store --test azurite_store_test locally:
upload_and_get_data, upload_empty_data, and
zero_len_items_exist_check all pass against a real AzureBlobStore
talking to a locally spawned Azurite instance no mocking. Two
#[ignore]d tests document manual verification of the SAS signer and
container-bootstrap logic, done independently before wiring them into
the automatic flow.

Also ran the full suite under Bazel/Nix per review feedback
(bazel-retry test //nativelink-store:integration ...): 25/27 pass.
The 2 known failures are azurite_store_test_test (Bazel's sandboxed
test execution has no network access to run bun install, so
azurite-blob isn't present at runtime, same root cause as the
p.mongodb symlink hack mongo_runner needs in flake.nix) and a
one-off grpc_store_test_test timeout that passes cleanly in
isolation, confirmed as resource pressure flakiness rather than a
real regression.

Fixed 11 Clippy findings surfaced by the Bazel/Nix run (import
ordering, tokio::spawn → nativelink_util::background_spawn!, doc
comment formatting, #[tokio::test] → #[nativelink_test], etc.),
and a Windows-specific bug where the runner looked for azurite-blob
without the .cmd extension npm/bun generate on that platform.

Could not verify bazel test //... (full monorepo) or the Nix-driven
pre-commit hooks directly at first, due to macOS 12/Monterey being
unsupported by the current Nix installer. Later verified both via an
Ubuntu VM once set up.

Risk

Low. This is purely additive test infrastructure, no production code
(azure_blob_store.rs itself) is touched beyond adapting one call site
to match its async/non-async signature after an unrelated upstream
Rust 1.97.1 toolchain bump changed it mid-review. New dev-only
dependencies (chrono, hmac) and a Bun-based install step affect
test builds and CI only, not the shipped nativelink binary. The known
gap is that the new Azurite tests don't yet execute under Bazel/Nix's
sandboxed test paths (see above), a coverage gap for this new suite,
not a regression, since the existing mocked azure_blob_store_test.rs
still runs everywhere unaffected.

AI assistance

Used GitHub Copilot to help diagnose several CI failure logs during
review (Clippy findings, a stale commit false positive on an
AzureBlobStore::new() signature question, and the PR-template check
itself), verified each suggestion against the actual source/log
output before applying, and caught at least one incorrect diagnosis
from it in the process.

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Project	Deployment	Actions	Updated
nativelink	Ready	Preview	Oct 5, 2026 10:09am UTC
nativelink-aidm	Ready	Preview	Oct 5, 2026 10:09am UTC

[CLAassistant]

All committers have signed the CLA.

[MarcusSorealheis]

Thank you for the PR. We will check it out soon!

[palfrey]

Thanks for doing this. There's a few issues though.

[palfrey]

I would suggest running all of this locally under Bazel with nix, so you can fix the variety of lint failures there as well as run pre-commit run -a to fix all the pre-commit issues currently being flagged in the build.

[Muktarsadiq]

Ran bazel-retry test //nativelink-store:integration under Nix. 25/27 pass. The 2 failures were azurite_store_test_test fails exactly as flagged in my earlier comment (sandbox has no network to run bun install), and grpc_store_test_test failed on an unrelated pre existing test with a hardcoded 5s timeout, which I believe was resource pressure flakiness on my VM rather than a real regression

[MarcusSorealheis]

@Muktarsadiq You are very close. Let me know if you need any help. The answer is in the logs here.