[FEATURE] Speed up Cypress E2E test suite (3m31s → 58s)

### Why do we need this improvement?

The Cypress E2E suite was slow due to:

1. Repeated cy.visit() calls
2. Overuse of beforeEach() for read-only tests
3. A skipped test caused by a nested it block
4. Retries enabled during local runs

### How will this change help?

1. toolspage.cy.js: Replaced beforeEach() with before() (page loaded once instead of 57 times)
~1m52s → ~1s
3. homepage.cy.js: Split navigation tests from verification tests ~47s → ~28s
5. docspage.cy.js: Fixed invalid nested it block so all tests run
6. Config:
7. Set testIsolation: false
8. Added test:e2e:fast (retries=0) for quick local feedback

### Screenshots

_No response_

### How could it be implemented/designed?

1. Reduce redundant reloads: Use before() instead of beforeEach() for read-only tests and share page state by disabling test isolation where safe.

2. Optimize test structure: Separate navigation tests from verification-only tests and avoid unnecessary external navigation (assert href instead).

### 🚧 Breaking changes

Yes

### 👀 Have you checked for similar open issues?

- [x] I checked and didn't find a similar issue

### 🏢 Have you read the Contributing Guidelines?

- [x] I have read the [Contributing Guidelines](https://github.com/asyncapi/.github/blob/master/CONTRIBUTING.md)

### Are you willing to work on this issue?

Yes I am willing to submit a PR!

The affected entry points are toolspage.cy.js, homepage.cy.js, docspage.cy.js, and the Cypress configuration; start by running test:e2e:fast and inspecting the existing setup hooks and retry settings. Separate navigation from verification, fix the nested it block, and verify the fast command and the reported suite-time improvement.

Written by the indexing model from the issue text.