chore: fix login integration (#10318)

# Which Problems Are Solved

Login integration tests are not executed in the pipeline

# How the Problems Are Solved

The login integration tests are fixed and added as a pipeline workflow.
It  tests against the built login docker image.
On pipeline failures, developers are guided on how to fix them using a
dev container configured for this purpose.

# Additional Changes

- email domains are replaced by example.com. In case the tests were
accidentally run against a cloud instance, it wouldn't cause bounces.
- pnpm is upgraded, because the --filter argument doesn't work for the
install command on the old version.
- The login Dockerfile is optimized for docker image builds

# Additional Changes From Review for
https://github.com/zitadel/zitadel/pull/10305

These changes were requested from @peintnermax 

- The base dev container starts without any services besides the
database and the dev container itself
- CONTRIBUTING.md is restructured
- To reproduce pipeline checks, only the devcontainer CLI and Docker are
needed. This is described in the CONTRIBUTING.md
- The convenience npm script "generate" is added

# Additional Context

- Follow-up for PR https://github.com/zitadel/zitadel/pull/10305
- Base for https://github.com/zitadel/zitadel/issues/10277

.devcontainer/base/commands/login-integration.post-attach.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" == "true" ]; then
+    set -e
+fi
+
+echo
+echo
+echo
+echo -e "THANKS FOR CONTRIBUTING TO ZITADEL 🚀"
+echo
+echo "Your dev container is configured for fixing login integration tests."
+echo "The login is running in a separate container with the same configuration."
+echo "It calls the mock-zitadel container which provides a mocked Zitadel gRPC API."
+echo
+echo "Also the test suite is configured correctly."
+echo "For example, run a single test file:"
+echo "pnpm cypress run --spec integration/integration/login.cy.ts"
+echo
+echo "You can also run the test interactively."
+echo "However, this is only possible from outside the dev container." 
+echo "On your host machine, run:"
+echo "cd apps/login"
+echo "pnpm cypress open"
+echo
+echo "If you want to change the login code, you can replace the login container by a hot reloading dev server."
+echo "docker stop login-integration"
+echo "pnpm turbo dev"
+echo "Navigate to the page you want to fix, for example:"
+echo "http://localhost:3001/ui/v2/login/verify?userId=221394658884845598&code=abc"
+echo "Change some code and reload the page for instant feedback."
+echo
+echo "When you are done, make sure all integration tests pass:"
+echo "pnpm cypress run"
+echo
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" != "true" ]; then
+    exit 0
+fi

.devcontainer/base/commands/login-integration.update-content.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" == "true" ]; then
+    echo "Running in fail-on-errors mode" 
+    set -e
+fi
+
+pnpm install --frozen-lockfile \
+    --filter @zitadel/login \
+    --filter @zitadel/client \
+    --filter @zitadel/proto  \
+    --filter zitadel-monorepo
+pnpm cypress install
+pnpm test:integration:login
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" != "true" ]; then
+    exit 0
+fi

.devcontainer/base/commands/turbo-lint-unit.post-attach.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" == "true" ]; then
+    set -e
+fi
+
+echo
+echo
+echo
+echo -e "THANKS FOR CONTRIBUTING TO ZITADEL 🚀"
+echo
+echo "Your dev container is configured for fixing linting and unit tests."
+echo "No other services are running alongside this container."
+echo
+echo "To fix all auto-fixable linting errors, run:"
+echo "pnpm turbo lint:fix"
+echo
+echo "To watch console linting errors, run:"
+echo "pnpm turbo watch lint --filter console"
+echo
+echo "To watch @zitadel/client unit test failures, run:"
+echo "pnpm turbo watch test:unit --filter @zitadel/client"
+echo
+echo "To watch @zitadel/login relevant unit tests and linting failures, run:"
+echo "pnpm turbo watch lint test:unit --filter @zitadel/login..."
+echo
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" != "true" ]; then
+    exit 0
+fi

.devcontainer/base/commands/turbo-lint-unit.update-content.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" == "true" ]; then
+    set -e
+fi
+
+pnpm install --frozen-lockfile --recursive
+pnpm turbo lint test:unit
+
+if [ "$FAIL_COMMANDS_ON_ERRORS" != "true" ]; then
+    exit 0
+fi