fix(test): inject AbortSignal/TextEncoder into the miner-extension-live-fetch vm sandbox

node:vm's createContext() is a fresh, isolated realm with none of the
outer process's globals. background.js's live-fetch path bounds its
fetch with AbortSignal.timeout(...) (#4c0b19f4) and measures the real
serialized byte size via TextEncoder for the quota guard (#7062), but
the test harness never injected either global into the sandbox --
every call on the success path threw "<Global> is not defined",
caught by the function's own try/catch and silently misreported as a
typed failure result instead of a real one.

Confirmed this isn't CI flakiness: reproduced deterministically outside
CI, on every run, for any candidates payload that reaches the success
path (all 4 of the 7 originally-failing tests exercise that path; the
other 3 return early on a non-2xx/malformed/thrown-fetch branch before
ever touching either global).

Author: JSONbored

test/unit/miner-extension-live-fetch.test.ts

@@ -75,6 +75,13 @@ function loadBackgroundWithFakeChrome({
     __LOOPOVER_MINER_EXTENSION_TEST__: true,
     chrome,
     fetch: fetchImpl,
+    // node:vm's createContext() is a fresh, isolated realm with none of the outer process's globals --
+    // background.js's live-fetch path bounds its fetch with AbortSignal.timeout(...) (#4c0b19f4) and
+    // measures the real serialized byte size via TextEncoder for the quota guard (#7062), so the sandbox
+    // needs both real globals injected or those calls throw "<Global> is not defined" on any payload that
+    // reaches the success path.
+    AbortSignal,
+    TextEncoder,
   };
   context.globalThis = context;
   const vmContext = createContext(context);