chore(examples): update nextjs example with next version (dotCMS#32150)

This pull request introduces several updates to the Next.js example
application, focusing on dependency upgrades, code refactoring, and new
features. The most notable changes include updating dependencies,
refactoring page handling logic, adding new components, and enhancing
the Tailwind CSS setup.

### Dependency and Configuration Updates:
* Updated `next` to version `15.3.2`, `react` and `react-dom` to
`19.1.0`, and other related dependencies in `package.json`. Added
`@tailwindcss/postcss` and updated Tailwind CSS to version `4.1.6` for
improved styling capabilities.
* Enabled `turbopack` in the development script by modifying the `dev`
command in `package.json`.

### Page Handling Refactor:
* Refactored the `[[...slug]]/page.js`, `blog/post/[[...slug]]/page.js`,
and `blog/page.js` files to use a unified `getDotCMSPage` utility for
fetching page data, replacing redundant logic and simplifying metadata
generation.
([examples/nextjs/src/app/[[...slug]]/page.jsL1-R13](diffhunk://#diff-ae32fed6c8c541fd820d195111a8c016ec33ecd22c5785374a4cb48e295c479bL1-R13)R1,
[examples/nextjs/src/app/blog/post/[[...slug]]/page.jsL1-R14](diffhunk://#diff-b407330cf92641b72b66d15e4c134e93224b6b10a9ededc2771705c259dab081L1-R14),
[examples/nextjs/src/app/blog/page.jsR1-R49](diffhunk://#diff-12cedd615b055bae3e41ba562068aff97a8239be8e3afacbb50de4b386aa2c0bR1-R49))
* Removed the `campaigns/[[...slug]]/page.js` file, consolidating its
functionality into the new page handling structure.
([examples/nextjs/src/app/campaigns/[[...slug]]/page.jsL1-L68](diffhunk://#diff-ab578cabb2e84be8de634e6781df0be7a59dc4cf13e7444672ecfe12f2faea8cL1-L68))

### Tailwind CSS Enhancements:
* Updated the Tailwind CSS setup in `globals.css` to use the `@import`
syntax and added custom utilities, themes, and plugins for better
styling flexibility.
[[1]](diffhunk://#diff-d08633dc30063defca3dd159cde6dcbfa912ce29719ccdd3dffb1e05eccee392L1-L19)
[[2]](diffhunk://#diff-d08633dc30063defca3dd159cde6dcbfa912ce29719ccdd3dffb1e05eccee392R45-R48)

### New Components:
* Added a `Header` component with navigation and an edit mode toggle,
improving the layout and user experience.
* Introduced a `RecommendedCard` component for displaying recommended
content with an edit button and improved styling.

### Codebase Simplification:
* Renamed and refactored the `Activity` component to improve readability
and styling consistency. Removed unused content type components and
their references.
[[1]](diffhunk://#diff-742e18d6505888f37e090e2737ec675ccae16978d0bb75bf7bc0702bf7a0064bL3-R15)
[[2]](diffhunk://#diff-5912745dd6534531e269707b918724caf3562c2a7e17b935d46f78d9d72ea638L1-L14)
* Removed legacy blog and activity content rendering logic from
`content-types/blog.js` and `content-types/index.js`.
[[1]](diffhunk://#diff-2092d48425507c2a8f3b5c781d2ef658167612d92673a999aaea88d09db46537L1-L34)
[[2]](diffhunk://#diff-5912745dd6534531e269707b918724caf3562c2a7e17b935d46f78d9d72ea638L1-L14)

These changes collectively modernize the application, streamline its
codebase, and improve maintainability.


### Video

### UVE



https://github.com/user-attachments/assets/6e15e610-0e55-4286-9f6b-3994e1c5fae4


### Dev environment


https://github.com/user-attachments/assets/3893a256-76a4-4b94-a313-f9812bd5bdee

Author: rjvelazco

.gitignore

@@ -184,4 +184,9 @@ dotCMS/dependencies.gradle
 
 # Vite config timestamp files
 **/*vite.config*.timestamp-*.mjs
-**/*vite.config*.timestamp-*.ts
+**/*vite.config*.timestamp-*.ts
+
+# Examples package-lock.json
+examples/nextjs/package-lock.json
+examples/angular/package-lock.json
+examples/astro/package-lock.json