Add theme selector

[victoria-lo]

We’d like to make this tool more community-agnostic and easily reusable by other tech groups (for example: open source meetups, developer community organisations, hackathon groups, etc). Right now it is branded and structured around ragTechDev, but with a few adjustments it could serve a wider audience.

Goals:

• Allow other tech communities to add their own brand (names, logos, colours) without needing deep code changes.
• Provide a clear onboarding path for new communities to fork/customise the project.
• Make configuration of templates (templates for social posts, event banners, etc) more flexible so communities can adapt text/layout/logo easily.
• Keep the core functionality (canvas export, platform sizes, etc) intact, but separate “branding assets” from core logic.

Sub-issues:

We’d like to make this tool more community-agnostic and easily reusable by other tech groups (for example: open source meetups, developer community organisations, hackathon groups, etc). Right now it is branded and structured around ragTechDev, but with a few adjustments it could serve a wider audience.

Goals:

• Allow other tech communities to add their own brand (names, logos, colours) without needing deep code changes.
• Provide a clear onboarding path for new communities to fork/customise the project.
• Make configuration of templates (templates for social posts, event banners, etc) more flexible so communities can adapt text/layout/logo easily.
• Keep the core functionality (canvas export, platform sizes, etc) intact, but separate “branding assets” from core logic.

Sub-issues:

• Add community configuration system #1
• Refactor template components to use config #2
• Add multi-community theme folder structure #3
• Add theme selector #4
• Update README and documentation #5
• Add example community preset #6
• Add automated test coverage #7

#4 Add theme selector

Goal: Allow developers to choose which community theme to load.

Description:
Introduce a simple way (via environment variable, CLI argument, or runtime option) to select which community’s theme to use when building or running the app.

Acceptance criteria:

• Add COMMUNITY environment variable or CLI flag.
• App loads correct theme folder accordingly.
• Document usage examples in README.
• Test switching between at least 3 themes.

Dependencies: #3