fix(ado-script): inline azure-devops-node-api to avoid missing ncc chunk

[jamesadevine]

Summary

exec-context-pr-synth (and latently gate.js) crashed at runtime with:

[synth-pr] listActivePullRequestsBySourceRef failed: Cannot find module
'/tmp/ado-aw-scripts/ado-script/485.index.js' imported from
/tmp/ado-aw-scripts/ado-script/exec-context-pr-synth.js

Root cause

src/shared/auth.ts lazy-loaded azure-devops-node-api via
await import("azure-devops-node-api") to defer ~50–100 ms of module
evaluation on bypass paths. ncc 0.38 compiles dynamic import() into a
separate webpack chunk file (<id>.index.js) that lives alongside
the main bundle in .ado-build/<name>/. Each build:* script in
scripts/ado-script/package.json only copies index.js out to the flat
<name>.js layout that the release workflow ships as individual assets
(see src/compile/extensions/ado_script.rs's per-file download list),
so the chunk silently vanished. At runtime getWebApi() tried
n.e(485).then(n.t.bind(n, 3485, 23)) and Node could not resolve the
missing file.

gate.js had the same chunk-split, but most gate evaluations short-
circuit before touching getWebApi(), so the bug stayed dormant there
until exec-context-pr-synth exercised the ADO REST path on every run.

Fix

Replace the dynamic import with a static import * as azdev in
src/shared/auth.ts. ncc now inlines the SDK directly into every
bundle, so each script ships as a single self-contained file that
matches the flat release layout:

bundle	dynamic chunks	size
gate.js	0	1 127 kB
import.js	0	2 kB
exec-context-pr.js	0	8 kB
exec-context-pr-synth.js	0	1 145 kB

Updated the doc comment on auth.ts to record why the import is static
(linking the failure mode to the flat release layout) and dropped the
now-stale 30 s vitest timeout in auth.test.ts that compensated for
the first-call dynamic-import cost.

Note

No compiler/Rust changes — the broken artefacts only ship via a new
ado-aw release that bundles scripts/ado-script/*.js as release
assets. A release of ado-aw is required before pipelines pick up
the fix end-to-end.

Test plan

From scripts/ado-script/:

• npm run typecheck — clean
• npm test — 281/281 passing (34 test files)
• npm run test:smoke — 6/6 passing
• npm run build — all four bundles rebuilt; verified each contains
  zero n.e(<id>) dynamic chunk loads via a regex sweep over the
  emitted *.js files.