Fix cwd-dependent WebAPP paths causing TemplateNotFound

[alwaysalearner1234]

Fix cwd-dependent WebAPP paths causing TemplateNotFound

Summary

Fixes incorrect WebAPP path resolution that depended on the current working directory.
When the app was launched from API/, Flask attempted to load templates from API/WebAPP/, causing:
jinja2.exceptions.TemplateNotFound: index.html

Changes

• Updated Config.py to resolve paths using Path(__file__).resolve() instead of Path('WebAPP')
• Updated app.py to configure template_folder and static_folder relative to the project root
• Fixed typo in EmissionActivityRatio parameter definition

Result

• / consistently renders WebAPP/index.html
• Execution location no longer affects path resolution
• Improved portability across macOS, Linux, and Windows

[SeaCelo]

Retargeted to mac-port per the macOS integration track: #51.
We are validating Mac/cross-platform changes in mac-port first, then merging mac-port -> main.