fix(e2e): let web-e2e:e2e run outside CI

Without CI, every web-e2e webServer has reuseExistingServer, so
@nx/playwright infers a continuous web:serve dependency for the
`pnpm nx run web:serve` entry. The mocks and the web backend launch as
plain node processes with env, which no Nx task covers, so the plugin
also marks the target non-parallel. Nx refuses a non-parallel task with
continuous dependencies, and `nx run web-e2e:e2e` failed before running
anything; CI passed only because CI=1 disables reuse and with it the
inferred dependency.

Give web-e2e:e2e an empty dependsOn so Playwright starts every server,
as it already does in CI. The Angular dev-server runs inside the Nx
process, so Playwright's process-group kill still stops it. Turn off
the plugin's readiness gate, which no target consumes any more.

Add `pnpm run e2e:task-graphs:validate`: it builds every Playwright
target's task graph with Nx's own validation, with CI unset and set,
and runs in the unit-and-typecheck job.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

nx.json

@@ -68,24 +68,28 @@
             "dependsOn": ["^build"],
             "inputs": ["production", "^production"]
         },
-        "e2e-ci--src/*.e2e.ts": {
-            "dependsOn": [
-                {
-                    "projects": ["electron-backend"],
-                    "target": "build-e2e"
-                },
-                {
-                    "projects": ["stalker-mock-server", "xtream-mock-server"],
-                    "target": "serve"
-                }
-            ]
-        }
+        "e2e-ci--src/*.e2e.ts": [
+            {
+                "filter": { "projects": ["electron-backend-e2e"] },
+                "dependsOn": [
+                    {
+                        "projects": ["electron-backend"],
+                        "target": "build-e2e"
+                    }
+                ]
+            },
+            {
+                "filter": { "projects": ["web-e2e"] },
+                "dependsOn": []
+            }
+        ]
     },
     "plugins": [
         {
             "plugin": "@nx/playwright/plugin",
             "options": {
-                "targetName": "e2e"
+                "targetName": "e2e",
+                "waitForWebServer": false
             }
         },
         {