✨ tests: add binary e2e suite (Traefik binary + Go mock LAPI), run it in CI

Add a second e2e suite that runs Traefik as a downloaded binary with the
plugin loaded from source, and replaces Crowdsec with a small stdlib-only Go
LAPI mock driven via /admin endpoints. No Docker, no real Crowdsec.

The mock lives in its own nested Go module (tests/e2e/mock/mocklapi) so it
stays out of the plugin module's build, lint, test and vendor.

This suite validates the plugin's own behaviour (live/none/stream modes,
caching, trusted-IP bypass, ban/captcha rendering). Crowdsec and AppSec
correctness are out of scope on purpose — they are validated upstream by the
maintainer — so the AppSec scenario is intentionally absent and the README
says so to avoid misfiled issues.

CI now runs this suite only (`make e2e_mock`), since it needs neither Docker
nor a real Crowdsec. The Docker suite (tests/e2e/scenarios) is kept for local
debugging (`make e2e`).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/e2e/mock/scenarios/stream-mode/dynamic.yml

@@ -0,0 +1,26 @@
+http:
+  routers:
+    r:
+      rule: "PathPrefix(`/foo`)"
+      entryPoints:
+        - web
+      service: backend
+      middlewares:
+        - bouncer
+  services:
+    backend:
+      loadBalancer:
+        servers:
+          - url: "@@BACKEND_URL@@"
+  middlewares:
+    bouncer:
+      plugin:
+        bouncer:
+          enabled: "true"
+          crowdsecMode: stream
+          updateIntervalSeconds: "2"
+          crowdsecLapiScheme: http
+          crowdsecLapiHost: "@@LAPI_HOST@@"
+          crowdsecLapiKey: "@@APIKEY@@"
+          forwardedHeadersTrustedIps:
+            - "127.0.0.1/32"