Add dedicated concept-evolution slide to the Chennai FOSS 2026 deck

[Copilot]

This updates the Chennai FOSS 2026 presentation to introduce the CI/CD template → Platform Engineering → IDP progression as its own slide, instead of burying the concept inside an existing section. The same change is mirrored in the Hugo static copy so both published deck paths stay aligned.

• Slide flow

  • Inserts a new Concept evolution slide immediately after Why DevOps-OS.
  • Leaves slide counting logic untouched since totals are already derived from .slide elements.

• Concept evolution diagram

  • Adds a pure HTML/CSS horizontal progression with three cards:
    • CI/CD template
    • Platform Engineering
    • IDP
  • Uses arrow separators to make the sequence read as an explicit maturity path rather than three independent points.

• Content updates

  • Adds short explanatory subtitles for each stage:
    • CI/CD template → automates stack setup
    • Platform Engineering → turns repeatable setup into shared internal capability
    • IDP → exposes that capability as a self-service developer experience
  • Adds a one-line maturity label and a footer takeaway to frame the progression clearly.

• Presentation styling

  • Introduces narrowly scoped layout classes for this slide only.
  • Reuses the deck’s existing card, gradient, border, and accent styling so the new slide matches the rest of the presentation.
  • Adds responsive behavior to collapse the 3-column layout into a stacked flow on smaller screens.

• Synced deck copies

  • Applies the same HTML/CSS changes to:
    • feature-announcements/chennai-foss-2026/index.html
    • hugo-docs/static/feature-announcements/chennai-foss-2026/index.html

<div class="concept-track" aria-label="CI/CD template evolves into platform engineering and then IDP">
  <div class="card concept-step">
    <h3>CI/CD template</h3>
    <p>Automates stack setup with repeatable pipelines, checks, and deployment defaults.</p>
  </div>
  <div class="concept-arrow" aria-hidden="true">→</div>
  <div class="card concept-step">
    <h3>Platform Engineering</h3>
    <p>Turns repeatable setup into an internal capability that standardises delivery without slowing teams down.</p>
  </div>
  <div class="concept-arrow" aria-hidden="true">→</div>
  <div class="card concept-step">
    <h3>IDP</h3>
    <p>Exposes that capability through a usable interface so developers can consume it as a self-service experience.</p>
  </div>
</div>