Update Hub Content and Title

[shreyaaithal]

Updates:

• Change webpage title to "PostgreSQL Hub for Azure Developers". Make necessary changes to styles, disclaimer, Readme.md, Contributing.md and Onboarding.md files
• Change description and tags for Learning pathways.
• Add 2 new resources: 1) Video - also featured, 2) Workshop: also part of AI Agents learning path.
• Remove duplicate blog entry for a solution accelerator (Agentic Shop) and mark the original as the featured resource.
• Update Label for Solution Accelerator filter to "Solution Accelerator (Sample App)"
• Update filter "Fundamentals" to "Database Service Fundamentals", and subfilter "Getting started" to "Deployment Quickstarts". Make necessary changes for sub-tag mapping.
• Quick links: Update links and description for quick links
• Community and support: Update "Events and Webinars" tile to add an event, add "Join the Community" tile, remove "Submit your ideas" tile and merge the CTA under "Contact Us" tile.