### What problem does this PR solve?

_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._

### Type of change: Documentation Update/Refactoring

#### Summary
Adds HTTPS/SSL configuration guide/example to enable secure RAGFlow
deployments with proper certificate management.

#### Changes
- New HTTPS Setup Section: Step-by-step guide for SSL certificate
configuration
- Let's Encrypt Integration: Complete Certbot setup instructions
- Docker Configuration: Volume mapping examples for certificates

#### Key Features
- Prerequisites checklist
- Docker Compose configuration examples
- Support for both Let's Encrypt and existing certificates

#### Files Modified
- `README.md`
- `ragflow.https.conf` (new file)

### What problem does this PR solve?


### Type of change


- [x] Refactoring

### What problem does this PR solve?

add the nginx path `/api` for sdk handlers 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### What problem does this PR solve?

feat: Display mindmap in drawer #2247

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

### What problem does this PR solve?

feat: Dynamically change the background image on the search homepage
every day #2247

### Type of change


- [x] New Feature (non-breaking change which adds functionality)

### What problem does this PR solve?

Related source file is in Windows/DOS format, they are format to Unix
format.

### Type of change

- [x] Refactoring

Signed-off-by: Jin Hai <haijin.chn@gmail.com>