fix: Correct capitalization of 'API' in execution flow documentation for consistency

Author: MariusStorhaug

specs/001-building-on-this/plan.md

@@ -8,7 +8,7 @@
 1. Load feature spec from Input path
    → If not found: ERROR "No feature spec at {path}"
 2. Fill Technical Context (scan for NEEDS CLARIFICATION)
-   → Detect Project Type from file system structure or context (web=frontend+backend, mobile=app+api)
+   → Detect Project Type from file system structure or context (web=frontend+backend, mobile=app+API)
    → Set Structure Decision based on project type
 3. Fill the Constitution Check section based on the content of the constitution document.
 4. Evaluate Constitution Check section below