feat: Add Helm repository installation instructions and index files

[felipegfalcao]

This pull request introduces support for deploying Hoppscotch using a Helm repository, updates chart versions for both Community and Enterprise editions, and adds an index.yaml file to facilitate Helm chart hosting. Below are the most important changes grouped by theme:

Helm Repository Support:

• Added a new section in README.md with instructions on how to add the Hoppscotch Helm repository and install charts for both Community and Enterprise editions. (README.md, README.mdR45-R67)

Chart Version Updates:

• Updated version and appVersion in charts/shc/Chart.yaml for the Community Edition to 2025.4.0. (charts/shc/Chart.yaml, charts/shc/Chart.yamlL5-R6)
• Updated version and appVersion in charts/she/Chart.yaml for the Enterprise Edition to 2025.4.0. (charts/she/Chart.yaml, charts/she/Chart.yamlL5-R6)

Helm Chart Index File:

• Added a new index.yaml file to define metadata for the Hoppscotch charts, including versions, URLs, and descriptions, enabling hosting on GitHub Pages. (index.yaml, index.yamlR1-R14)

[jonathanfoster]

@felipegfalcao Good call putting this together. Was just trying to install Hoppscotch, but couldn’t find the Helm repo anywhere.

Looks like the chart version in the PR is using a date-ish versioning scheme. We should stick to semver for chart versioning. This way users can differentiate major, minor, and patch updates.