Hardcode Firecrawl API endpoint, drop FIRECRAWL_ENDPOINT config

Firecrawl has a single public API at https://api.firecrawl.dev/v2.
The endpoint was configurable but never varied across environments,
so hardcode it as a package-level const and remove the Endpoint
field from FirecrawlConfig and all downstream wiring (bootstrap,
Helm chart, probod, vetting, cookiebanner).

Signed-off-by: Émile Ré <emile@probo.com>

pkg/bootstrap/builder.go

@@ -177,8 +177,7 @@ func (b *Builder) Build() (*probodconfig.FullConfig, error) {
 				},
 			},
 			Firecrawl: probodconfig.FirecrawlConfig{
-				Endpoint: b.getEnv("FIRECRAWL_ENDPOINT"),
-				APIKey:   b.getEnv("FIRECRAWL_API_KEY"),
+				APIKey: b.getEnv("FIRECRAWL_API_KEY"),
 			},
 			Agents: probodconfig.AgentsConfig{
 				Providers: map[string]probodconfig.LLMProviderConfig{