docs: Update project specs and align statuses

- Add Timber to technical decisions in tech_spec.txt
- Update feature statuses to 'backend_implemented' in tech_spec.txt
- Update UI component statuses to 'needs_review' in project_structure.txt

domain/src/main/java/com/homebox/lens/domain/model/TokenResponse.kt

@@ -0,0 +1,4 @@
+package com.homebox.lens.domain.model
+
+class TokenResponse {
+}