fix(build): auto-run api-gen when generated files are missing

[neptunix]

Problem

go build fails after a plain git clone because the generated API files (api/clickupv{2,3}/*.gen.go, internal/apiv{2,3}/operations.gen.go) are gitignored. This produces 14 compile errors for types that only exist in the generated code:

internal/apiv3/chat.go: undefined: GetChatChannelsParams
pkg/cmdutil/status.go: undefined: apiv2.GetSpace
... (14 total)

Any Dockerfile or CI pipeline that does git clone && go build is broken.

Fix

One line added to the build target — if the generated files are absent, run make api-gen first:

build:
	@[ -f api/clickupv3/client.gen.go ] || $(MAKE) api-gen
	go build ...

Verification

git clone https://github.com/triptechtravel/clickup-cli && cd clickup-cli
rm -f api/clickupv2/*.gen.go api/clickupv3/*.gen.go internal/apiv*/operations.gen.go
make build   # triggers api-gen then builds successfully