feat(gen): support custom templates for model generation

[Truongquangkhang]

• Do only one thing
• Non breaking API changes
• Tested

What did this pull request do?

• This MR adds support for custom templates in the model generation process, allowing consumers to inject additional generated code (e.g. filters, helper methods, DTOs) alongside default GORM Gen outputs.

User Case Description

A typical use case is generating:

• {Model}Filter structs for dynamic query building

• Common helper methods such as ToMap() for update operations or generic payload handling

• result

[propel-code-bot]

LGTM, ship it! 🚢

Details

Why was this auto-approved?

✅ APPROVED: No issues detected.

[propel-code-bot]

Support generator custom model templates

Introduces a way to inject custom text/templates into generated model files. Adds storage for per-model template snippets and ensures they are rendered during both model and query code generation flows.

Key Changes

• Added new method Generator.ApplyCustomTemplateForModel to broadcast a template string across all tracked model metas
• Extended generate.QueryStructMeta with a CustomTemplates slice for template text storage
• Hooked template rendering into generateModelFile and generateSingleQueryFile so custom templates are executed before user-defined model methods

Affected Areas

• generator.go
• internal/generate/query.go

This summary was automatically generated by @propel-code-bot