fix: escalate --ladder on Google Search block pages

docs/CLI_REFERENCE.md

@@ -200,7 +200,7 @@ field came back empty — one field matching is enough to count it as extracted.
 
 This is the closest pobear gets to reporting a soft block it doesn't recognize. A
 `200` challenge page from a known anti-bot vendor (Amazon's CAPTCHA, Cloudflare,
-DataDome, PerimeterX) is classified as `[blocked]` like a `403`, so `--ladder`
+DataDome, PerimeterX, Google Search) is classified as `[blocked]` like a `403`, so `--ladder`
 climbs past it; any other interstitial answers with a normal `200` and real HTML.
 What pobear can say is that the selectors you asked for found nothing, which is the same signal a
 challenge page, a layout change, or a wrong selector all produce. `empty 200` out

docs/JOB_SPEC_REFERENCE.md

@@ -170,7 +170,7 @@ reports which tier actually served each URL, whether or not `ladder` ever climbe
 
 On `local` and `proxy`, `blocked` covers `403`, `503`, and a `2xx` whose body is a
 recognized anti-bot page (Amazon's CAPTCHA, a Cloudflare challenge, DataDome,
-PerimeterX). Markers are vendor-specific, so an unrecognized challenge page still
+PerimeterX, Google Search's block page). Markers are vendor-specific, so an unrecognized challenge page still
 comes back as a successful fetch.
 
 **`profile` only spoofs the TLS ClientHello, nothing else:** it doesn't touch

services/core/internal/fetch/tiers/http.go

@@ -95,6 +95,7 @@ var blockPageMarkers = [][]byte{
 	[]byte("_cf_chl_opt"),          // Cloudflare challenge
 	[]byte("captcha-delivery.com"), // DataDome
 	[]byte("px-captcha"),           // PerimeterX
+	[]byte("emsg=SG_REL"),          // Google Search
 }
 
 func isBlockPage(body []byte) bool {

services/core/internal/fetch/tiers/local_test.go

@@ -77,6 +77,15 @@ func TestLocalFetch(t *testing.T) {
 			wantFault:  fault.Blocked,
 			wantErr:    true,
 		},
+		{
+			name: "200-google-search-block-is-blocked",
+			handler: func(w http.ResponseWriter, r *http.Request) {
+				_, _ = w.Write([]byte(`<a href="/search?q=x&amp;emsg=SG_REL&amp;sei=y">click here</a>`))
+			},
+			wantStatus: 200,
+			wantFault:  fault.Blocked,
+			wantErr:    true,
+		},
 		{
 			name: "200-mentioning-captcha-is-ok",
 			handler: func(w http.ResponseWriter, r *http.Request) {