Initial commit: CI Agent competitive-intelligence monitoring app

FastAPI + Celery + Next.js + Postgres/Redis app with company monitoring,
source collection, LLM-based change analysis, enrichment, and account
security (Turnstile, escalating lockout, email verification).

apps/api/app/core/errors.py

@@ -0,0 +1,46 @@
+"""App-level exceptions, mapped to HTTP responses in one place (main.py).
+
+Services raise these instead of `fastapi.HTTPException` so business logic
+stays importable/testable from Celery tasks, which don't have an HTTP
+response to raise into.
+"""
+
+from __future__ import annotations
+
+
+class AppError(Exception):
+    """Base class for all app-level errors."""
+
+
+class NotFoundError(AppError):
+    pass
+
+
+class ConflictError(AppError):
+    pass
+
+
+class AuthenticationError(AppError):
+    pass
+
+
+class ForbiddenError(AppError):
+    pass
+
+
+class ValidationAppError(AppError):
+    pass
+
+
+class RateLimitedError(AppError):
+    pass
+
+
+class ThrottledError(RateLimitedError):
+    """Raised by the IP throttle/ban engine (app/services/ip_throttle_service.py)
+    - carries a machine-readable retry_after_seconds so the frontend can
+    drive a live countdown instead of just showing a generic message."""
+
+    def __init__(self, message: str, retry_after_seconds: int | None = None) -> None:
+        super().__init__(message)
+        self.retry_after_seconds = retry_after_seconds