feat: migrate to pyproject.toml, add test suites, split CI workflows

- Replace requirements.txt with pyproject.toml for modern Python packaging
- Add unit, integration, lint and security test suites under tests/
- Add utils/export_runtime_requirements.py and utils/check_hadolint_sarif.py
- Split monolithic CI into reusable lint.yml, security.yml and tests.yml
- Refactor ci.yml to orchestrate reusable workflows; publish on semver tag only
- Modernize Dockerfile: pin python:3.12-slim, install via pyproject.toml
- Expand Makefile with lint, security, test and CI targets
- Add test-e2e via act with portfolio container stop/start around run
- Fix navbar_logo_visibility.spec.js: win.fullscreen() → win.enterFullscreen()
- Set use_reloader=False in app.run() to prevent double-start in CI
- Add app/core.* and build artifacts to .gitignore
- Fix apt-get → sudo apt-get in tests.yml e2e job
- Fix pip install --ignore-installed to handle stale act cache

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Makefile

@@ -7,6 +7,8 @@ endif
 
 # Default port (can be overridden with PORT env var)
 PORT ?= 5000
+PYTHON ?= python3
+ACT ?= act
 
 # Default port (can be overridden with PORT env var)
 .PHONY: build
@@ -14,10 +16,15 @@ build:
 	# Build the Docker image.
 	docker build -t application-portfolio .
 
+.PHONY: build-no-cache
+build-no-cache:
+	# Build the Docker image without cache.
+	docker build --no-cache -t application-portfolio .
+
 .PHONY: up
 up:
 	# Start the application using docker-compose with build.
-	docker-compose up -d --build
+	docker-compose up -d --build --force-recreate
 
 .PHONY: down
 down:
@@ -75,8 +82,93 @@ browse:
 	# Open the application in the browser at http://localhost:$(PORT)
 	chromium http://localhost:$(PORT)
 
+.PHONY: install
+install:
+	# Install runtime Python dependencies from pyproject.toml.
+	$(PYTHON) -m pip install -e .
+
+.PHONY: install-dev
+install-dev:
+	# Install runtime and developer dependencies from pyproject.toml.
+	$(PYTHON) -m pip install -e ".[dev]"
+
+.PHONY: npm-install
 npm-install:
+	# Install Node.js dependencies for browser tests.
 	cd app && npm install
 
-test: npm-install
-	cd app && npx cypress run --spec "cypress/e2e/**/*.spec.js"
+.PHONY: lint-actions
+lint-actions:
+	# Lint GitHub Actions workflows.
+	docker run --rm -v "$$PWD:/repo" -w /repo rhysd/actionlint:latest
+
+.PHONY: lint-python
+lint-python: install-dev
+	# Run Python lint and format checks.
+	$(PYTHON) -m ruff check .
+	$(PYTHON) -m ruff format --check .
+
+.PHONY: lint-docker
+lint-docker:
+	# Lint the Dockerfile.
+	docker run --rm -i hadolint/hadolint < Dockerfile
+
+.PHONY: test-lint
+test-lint:
+	# Run lint guardrail tests.
+	$(PYTHON) -m unittest discover -s tests/lint -t .
+
+.PHONY: test-integration
+test-integration: install
+	# Run repository integration tests.
+	$(PYTHON) -m unittest discover -s tests/integration -t .
+
+.PHONY: test-unit
+test-unit: install
+	# Run repository unit tests.
+	$(PYTHON) -m unittest discover -s tests/unit -t .
+
+.PHONY: test-security
+test-security: install
+	# Run repository security guardrail tests.
+	$(PYTHON) -m unittest discover -s tests/security -t .
+
+.PHONY: lint
+lint: lint-actions lint-python lint-docker test-lint
+	# Run the full lint suite.
+
+.PHONY: security
+security: install-dev test-security
+	# Run security checks.
+	$(PYTHON) -m bandit -q -ll -ii -r app main.py
+	$(PYTHON) utils/export_runtime_requirements.py > /tmp/portfolio-runtime-requirements.txt
+	$(PYTHON) -m pip_audit -r /tmp/portfolio-runtime-requirements.txt
+
+.PHONY: test-e2e
+test-e2e:
+	# Run Cypress end-to-end tests via act (stop portfolio container to free port first).
+	-docker stop portfolio 2>/dev/null || true
+	$(ACT) workflow_dispatch -W .github/workflows/tests.yml -j e2e
+	-docker start portfolio 2>/dev/null || true
+
+.PHONY: test-workflow
+test-workflow:
+	# Run the GitHub test workflow locally via act.
+	$(ACT) workflow_dispatch -W .github/workflows/tests.yml
+
+.PHONY: lint-workflow
+lint-workflow:
+	# Run the GitHub lint workflow locally via act.
+	$(ACT) workflow_dispatch -W .github/workflows/lint.yml
+
+.PHONY: quality
+quality: lint-workflow test-workflow
+	# Run the GitHub lint and test workflows locally via act.
+
+.PHONY: ci
+ci: lint security test-unit test-integration test-e2e
+	# Run the local CI suite.
+
+.PHONY: test
+test: ci
+	# Run the full validation suite.