refactor: rename public routes and templates to platform

Complete the public -> platform naming migration across the codebase.
This aligns with the naming convention where "platform" refers to
the marketing/public-facing pages of the platform itself.

Changes:
- Update all imports from public to platform modules
- Update template references from public/ to platform/
- Update route registrations to use platform prefix
- Update documentation to reflect new naming
- Update test files for platform API endpoints

Files affected:
- app/api/main.py - router imports
- app/modules/*/routes/*/platform.py - route definitions
- app/modules/*/templates/*/platform/ - template files
- app/modules/routes.py - route discovery
- docs/* - documentation updates
- tests/integration/api/v1/platform/ - test files

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/testing/test-structure.md

@@ -31,7 +31,7 @@ The test structure directly mirrors the API code structure:
 ```
 app/api/v1/admin/     →  tests/integration/api/v1/admin/
 app/api/v1/vendor/    →  tests/integration/api/v1/vendor/
-app/api/v1/public/    →  tests/integration/api/v1/public/
+app/api/v1/platform/    →  tests/integration/api/v1/platform/
 app/api/v1/shared/    →  tests/integration/api/v1/shared/
 ```
 
@@ -83,7 +83,7 @@ Different teams can work in parallel with fewer conflicts:
 ```
 Admin Team:   works in tests/integration/api/v1/admin/
 Vendor Team:  works in tests/integration/api/v1/vendor/
-Public Team:  works in tests/integration/api/v1/public/
+Public Team:  works in tests/integration/api/v1/platform/
 ```
 
 ## Running Tests
@@ -98,7 +98,7 @@ pytest tests/integration/api/v1/vendor/ -v
 pytest tests/integration/api/v1/admin/ -v
 
 # All public tests
-pytest tests/integration/api/v1/public/ -v
+pytest tests/integration/api/v1/platform/ -v
 
 # All shared tests
 pytest tests/integration/api/v1/shared/ -v
@@ -277,7 +277,7 @@ See [Vendor API Testing Guide](vendor-api-testing.md) for details.
 
 ### Public Tests (`public/`)
 
-Tests for public endpoints at `/api/v1/public/*`:
+Tests for public endpoints at `/api/v1/platform/*`:
 
 - Product catalog browsing
 - Public vendor profiles