Docker Image Updates and Security Enhancements (#1)

# Overview
This PR introduces several improvements to our Docker infrastructure, focusing on security, base image optimization, and workflow automation.

# Key Changes

## Base Image Updates
- Updated system package installation and cleanup processes

## Security Enhancements
- Implemented Trivy security scanning in the Dockerfile
- Adjusted Trivy scan configuration to handle known Debian vulnerabilities
- Enhanced container security by ensuring proper ownership of `/workspaces` directory

## CI/CD Improvements
- Added manual workflow dispatch capability to Docker workflows
- Implemented cron scheduling for automated builds
- Enhanced Docker image configuration and build process

# Technical Details
- Trivy security scanning is now implemented using a script-based installation method
- Workflow improvements allow both scheduled and manual triggering of Docker builds

# Security Considerations
- Trivy scan exit code has been set to 0 to accommodate known Debian vulnerabilities while maintaining security awareness
- Proper directory permissions and ownership are maintained for `/workspaces`

# Impact
These changes improve our Docker image by:
- Reducing image size and improving build efficiency
- Enhancing security scanning capabilities
- Providing more flexible deployment options through manual triggers
- Ensuring consistent automated builds through cron scheduling

# Reviewer Notes
Please pay special attention to:
- The base image change and its impact on existing workflows
- Security scanning configuration
- Workflow trigger modifications

Reviewed-on: #1
Co-authored-by: Guiillaume Hemmen <guillaume@van-hemmen.com>
Co-committed-by: Guiillaume Hemmen <guillaume@van-hemmen.com>

.forgejo/workflows/docker-dev.yaml

@@ -2,6 +2,7 @@ on:
   push:
     branches-ignore:
       - 'master'
+  workflow_dispatch:
 jobs:
   docker-dev:
     runs-on: docker

.forgejo/workflows/docker-master.yaml

@@ -2,6 +2,9 @@ on:
   push:
     branches:
       - 'master'
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch:
 jobs:
   docker-master:
     runs-on: docker

.forgejo/workflows/docker-pr.yaml

@@ -1,5 +1,6 @@
 on:
   pull_request:
+  workflow_dispatch:
 
 jobs:
   docker-pr: