build: update to node 22 and pnpm (#3616)

This commit brings the project to support node 22 which became LTS and
fixes broken builds with typescript 5.7+ until vue-tsc is updated and
replaces npm with pnpm.

- Update tsconfig for node 22
- Pin typescript to 5.6.x to not break vue-tsc
- Replace npm with pnpm (corepack recommended)
- Update Makefile and main workflow for pnpm
- Migrate to eslint 9 flat config
- Fix broken imports
- Exclude non-TS vue files for vue-tsc

Makefile

@@ -10,7 +10,7 @@ build: | build-frontend build-backend ## Build binary
 
 .PHONY: build-frontend
 build-frontend: ## Build frontend
-	$Q cd frontend && npm ci && npm run build
+	$Q cd frontend && pnpm install --frozen-lockfile && pnpm run build
 
 .PHONY: build-backend
 build-backend: ## Build backend
@@ -21,6 +21,7 @@ test: | test-frontend test-backend ## Run all tests
 
 .PHONY: test-frontend
 test-frontend: ## Run frontend tests
+	$Q cd frontend && pnpm install --frozen-lockfile && pnpm run typecheck
 
 .PHONY: test-backend
 test-backend: ## Run backend tests
@@ -31,7 +32,7 @@ lint: lint-frontend lint-backend ## Run all linters
 
 .PHONY: lint-frontend
 lint-frontend: ## Run frontend linters
-	$Q cd frontend && npm ci && npm run lint
+	$Q cd frontend && pnpm install --frozen-lockfile && pnpm run lint
 
 .PHONY: lint-backend
 lint-backend: | $(golangci-lint) ## Run backend linters
@@ -65,4 +66,4 @@ help: ## Show this help
 	@awk 'BEGIN {FS = ":.*?## "} { \
 		if (/^[a-zA-Z_-]+:.*?##.*$$/) {printf "    ${YELLOW}%-20s${GREEN}%s${RESET}\n", $$1, $$2} \
 		else if (/^## .*$$/) {printf "  ${CYAN}%s${RESET}\n", substr($$1,4)} \
-		}' $(MAKEFILE_LIST)
+		}' $(MAKEFILE_LIST)