Add validation constraints for repository creation fields

[lunny]

Adds validation constraints to repository creation inputs, enforcing max-length limits for labels/gitignores/license/readme and enum validation for trust model and object format. Updates both the API option struct and the web form struct to keep validation consistent.

[KN4CK3R]

Other fields like Gitignores are no problem?

[lunny]

Other fields like Gitignores are no problem?

Only the License field among the repository creation parameters is used as a database query/insert parameter.

[lunny]

Other fields like Gitignores are no problem?

These restrictions have been added to enforce stricter validation and prevent potential issues or unnecessary problems.

[Copilot]

Pull request overview

This pull request adds input validation constraints to repository creation form fields and API options, limiting the size of various string fields to prevent potential issues with excessively long input values.

Changes:

• Added MaxSize validation to License (100), Gitignores (255), IssueLabels (255), Readme (255), and ForkSingleBranch (255) fields
• Added enum validation with In() to ObjectFormatName (sha1, sha256) and TrustModel (default, collaborator, committer, collaboratorcommitter) fields
• Applied validation consistently to both web form structs (CreateRepoForm) and API structs (CreateRepoOption)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
services/forms/repo_form.go	Added MaxSize and In() validation tags to CreateRepoForm fields for web form validation
modules/structs/repo.go	Added MaxSize and In() validation tags to CreateRepoOption fields for API validation

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[silverwind]

Update PR title please to reflect that it's not only license.