test(market): restore HAHA_MARKET_DISABLE_PROVIDERS instead of deleting it

afterEach deleted the variable outright, so a developer who exported it to
silence a provider lost it after the first test file ran. The
essential-traffic variable next to it was already saved and restored; this
makes both behave the same way, since neither belongs to the test.

19 pass / 0 fail with the variable inherited from `.env`, with an explicit
CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1, and with
HAHA_MARKET_DISABLE_PROVIDERS=skillhub set in the environment — the case
that previously came back unset.

src/server/__tests__/market-providers.test.ts

@@ -16,6 +16,7 @@ type FetchStub = (url: string) => { status?: number; body: string; contentType?:
 
 let requestedUrls: string[] = []
 let originalNonEssentialTrafficEnv: string | undefined
+let originalDisableProvidersEnv: string | undefined
 const originalFetch = globalThis.fetch
 
 function stubFetch(handler: FetchStub) {
@@ -35,6 +36,7 @@ beforeEach(() => {
   requestedUrls = []
   resetMarketCacheForTests()
   resetClawhubOwnerCacheForTests()
+  originalDisableProvidersEnv = process.env.HAHA_MARKET_DISABLE_PROVIDERS
   delete process.env.HAHA_MARKET_DISABLE_PROVIDERS
   // These tests stub upstreams and must not inherit the developer shell's
   // essential-traffic env (which would block the market providers entirely).
@@ -44,7 +46,12 @@ beforeEach(() => {
 
 afterEach(() => {
   globalThis.fetch = originalFetch
-  delete process.env.HAHA_MARKET_DISABLE_PROVIDERS
+  // Restore rather than delete: these are the developer's variables, not ours.
+  if (originalDisableProvidersEnv === undefined) {
+    delete process.env.HAHA_MARKET_DISABLE_PROVIDERS
+  } else {
+    process.env.HAHA_MARKET_DISABLE_PROVIDERS = originalDisableProvidersEnv
+  }
   if (originalNonEssentialTrafficEnv === undefined) {
     delete process.env.CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC
   } else {