CI: replace invalid placeholder APP_SHARED_SECRET in Run Tests & Build Check

[Copilot]

The Run Tests & Build Check workflow failed because CI used the development placeholder APP_SHARED_SECRET, which is rejected by production-mode config validation at test startup. This change updates CI to use a non-placeholder secret value consistently across test and build steps.

• Root cause alignment

  • Replaced dev-insecure-client-shared-secret-min-32-chars-long in workflow env with a CI-safe non-placeholder secret so config bootstrap no longer exits in production mode.

• Workflow consistency

  • Updated both Run Tests and Build Test API & TUI steps to use the same APP_SHARED_SECRET.
  • Updated TUI -ldflags default app secret injection to match the same CI value.

- name: Run Tests
  env:
    APP_SHARED_SECRET: ci-test-shared-secret-not-for-production-usage-32
  run: go test -v ./...

- name: Build Test API & TUI
  env:
    APP_SHARED_SECRET: ci-test-shared-secret-not-for-production-usage-32
  run: |
    go build -v ./cmd/api
    go build -ldflags "-X main.DefaultAppSecret=ci-test-shared-secret-not-for-production-usage-32" -v ./cmd/tui

[DanielJohn17]

Done locally