NIFI-15908: Disabling the Apply button in the Connector wizard when t…

[mcgilman]

…here are no pending edits.

Summary

NIFI-15908

Disables the Connector wizard's Apply button when the backend reports there
is nothing to apply (e.g. no pending working-configuration changes, or a prior
apply still in progress) and surfaces the backend-supplied reason as a tooltip
on hover so the user can discover why the action is unavailable.

Background

The connector entity exposes an availableActions array; the APPLY_UPDATES
action carries allowed: boolean and reasonNotAllowed: string. The framework
already populates these correctly:

• "No pending changes" when the working configuration matches the active
  configuration.
• "Connector is updating" while a previous apply is PREPARING_FOR_UPDATE or
  UPDATING.

Until now the wizard ignored the action and only gated Apply on local UI state
(loading / applying / verifying / verification-passed). This PR threads the
backend signal through the wizard store into the summary step, then surfaces
the reason as a tooltip on the disabled button.

Changes

Wizard state plumbing

• with-connector-wizard.feature.ts — derives applyUpdatesAllowed and
  applyUpdatesDisabledReason computed signals from the connector's
  APPLY_UPDATES action via the existing getConnectorAction() helper.
• connector-wizard.store.ts — adds the two new signals to the abstract
  ConnectorWizardStore contract.
• connector-wizard.component.html — passes the signals down to the summary
  step as [applyAllowed] / [applyDisabledReason] inputs.

Summary step UI

• connector-configuration-summary-step.component.ts — adds applyAllowed
  (default true, preserving existing callers) and applyDisabledReason
  signal inputs; updates applyDisabled and applyTooltip computed signals
  so the backend reason takes precedence over the verify-required hint.
• connector-configuration-summary-step.component.html — binds
  [matTooltip]="applyTooltip()" plus a local [matTooltipShowDelay]="500".
  The tooltip lives directly on the <button> rather than on a wrapping
  <span>, made possible by the SCSS rule below.
• connector-configuration-summary-step.component.scss — re-enables
  pointer-events: auto on button[disabled] inside this component so the
  Material tooltip directive receives the hover events the browser would
  otherwise suppress on a native disabled button. Adds
  cursor: not-allowed for visual affordance.

Test coverage

• connector-configuration-summary-step.component.spec.ts — 5 new tests
  covering: disable state when applyAllowed=false overrides
  verificationPassed=true; tooltip surfacing the backend reason verbatim;
  the verify-required hint still wins when no backend reason is present;
  default values preserve existing-caller behavior.
• connector-wizard.store.spec.ts — 5 new tests against the
  applyUpdatesAllowed / applyUpdatesDisabledReason selectors covering:
  no connector / missing action / allowed=true / allowed=false with
  reason / allowed=false without reason (verifies the ?? '' fallback).
• connector-wizard.component.spec.ts — createMockStore factory updated
  to expose the two new signals so the mock continues to fully implement
  the abstract ConnectorWizardStore contract (prevents a future
  "is not a function" failure in tests that render the summary step).

Tracking

Please complete the following tracking steps prior to pull request creation.

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number NIFI-15908
• Pull Request commit message starts with Apache NiFi Jira issue number NIFI-15908
• Pull request contains commits signed with a registered key indicating Verified status

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

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Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25
• Frontend verified with nx test shared (725/725 passing) and
  nx lint shared (clean) from nifi-frontend/src/main/frontend

Licensing

• No new dependencies introduced
• N/A — no LICENSE/NOTICE updates required

Documentation

• N/A — UI behavior change with no user-facing documentation impact