feat(jira-dashboard): add new frontend homepage widget

[joecombopiano]

Summary

• add a native HomePageWidgetBlueprint for Jira issues assigned to the signed-in user
• register the widget in the Jira dashboard alpha frontend plugin
• expose title, filter, result limit, table, styling, and Jira link configuration
• isolate the alpha entrypoint from the legacy package entrypoint and core compatibility bridge for Studio/module-federation support
• preserve the legacy plugin exports and API ref ID for backwards compatibility
• add extension coverage, documentation, API report updates, dependencies, and a changeset

Validation

• verified the widget schema and component contract against the pinned Backstage frontend APIs
• verified the frontend API ref remains type-compatible with the legacy plugin factory
• Prettier, JSON, lockfile, and git diff checks pass
• full Jest execution could not run because the existing dependency graph resolves js-yaml 4.3.1, which the configured registry returns as 404

[changeset-bot]

🦋 Changeset detected

Latest commit: b94fb33

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@axis-backstage/plugin-jira-dashboard	Minor

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[fridajac]

Nice, thanks!

[joecombopiano]

@fridajac just fyi, we released a skill in opensource for making this easy :) https://github.com/backstage/backstage/blob/master/docs/.well-known/skills/app-frontend-system-migration/SKILL.md