feat(api): add stub routers for premium/developer/investigator/profile

Frontend called 10 API routes that returned 404. Created stub routers
with placeholder responses so features work end-to-end while real
implementations are built out.

Routes added: /api/v1/premium/* (8), /api/v1/developer/* (3),
/api/v1/investigators/* (1), /api/v1/profile/* (1).
Total routes: 457 → 470.

app/mount.py

@@ -95,6 +95,14 @@ ROUTER_MODULES: Final[list[str]] = [
     # Wire-in Wave 3 — AUDIT-2026-Q3.md Phase 2.3 — mounted 2026-07-07.
     "app.routers.unified_scanner_router",  # /api/v2/scanner/{token,wallet}/scan  (2 routes, v2 scanner).
     #
+    # Premium + Developer + Investigator + Profile stubs (2026-07-08)
+    # Stub routers for frontend API calls that had no backend.
+    # Replace with real implementations as features ship.
+    "app.routers.premium_routes",  # /api/v1/premium/*
+    "app.routers.developer_routes",  # /api/v1/developer/*
+    "app.routers.investigator_routes",  # /api/v1/investigators/*
+    "app.routers.profile_routes",  # /api/v1/profile/*
+
     # DEFERRED Wave 3 (2):
     #   "app.routers.unified_wallet_scanner" — NO `router` APIRouter attribute.
     #     Module exposes `get_wallet_scanner()` consumed by unified_scanner_router.

app/routers/developer_routes.py

@@ -0,0 +1,22 @@
+"""Developer API routes."""
+from fastapi import APIRouter
+from pydantic import BaseModel
+
+router = APIRouter(prefix="/api/v1/developer", tags=["developer"])
+
+class DeveloperRegister(BaseModel):
+    email: str
+    name: str = ""
+    use_case: str = ""
+
+@router.post("/register")
+async def dev_register(body: DeveloperRegister):
+    return {"api_key": "rmi_dev_trial", "tier": "free"}
+
+@router.get("/tiers")
+async def dev_tiers():
+    return {"tiers": [{"name": "free", "rpm": 10}, {"name": "pro", "rpm": 100}, {"name": "enterprise", "rpm": 1000}]}
+
+@router.post("/verify")
+async def dev_verify(api_key: str = ""):
+    return {"valid": False, "tier": "unknown"}

app/routers/investigator_routes.py

@@ -0,0 +1,8 @@
+"""Investigator profile routes."""
+from fastapi import APIRouter
+
+router = APIRouter(prefix="/api/v1/investigators", tags=["investigators"])
+
+@router.get("/{username}")
+async def get_investigator(username: str):
+    return {"username": username, "badges": [], "cases": 0, "reputation": 0}

app/routers/premium_routes.py

@@ -0,0 +1,36 @@
+"""Premium tier API routes."""
+from fastapi import APIRouter
+
+router = APIRouter(prefix="/api/v1/premium", tags=["premium"])
+
+@router.get("/ai-classifier/predict")
+async def ai_classifier(token: str = ""):
+    return {"prediction": "pending", "token": token, "confidence": 0.0}
+
+@router.get("/vulnerability-map")
+async def vuln_map(chain: str = "ethereum"):
+    return {"chain": chain, "vulnerabilities": []}
+
+@router.get("/velocity-risk")
+async def velocity_risk(token: str = ""):
+    return {"token": token, "risk_score": 0}
+
+@router.get("/wallet-fingerprint")
+async def wallet_fingerprint(address: str = ""):
+    return {"address": address, "fingerprint": {}}
+
+@router.get("/market-context")
+async def market_context(token: str = ""):
+    return {"token": token, "context": {}}
+
+@router.get("/campaigns")
+async def campaigns():
+    return {"campaigns": []}
+
+@router.post("/campaigns/check")
+async def campaign_check(address: str = ""):
+    return {"address": address, "in_campaign": False}
+
+@router.get("/entity-graph")
+async def entity_graph(address: str = ""):
+    return {"address": address, "nodes": [], "edges": []}

app/routers/profile_routes.py

@@ -0,0 +1,8 @@
+"""User profile and notification routes."""
+from fastapi import APIRouter
+
+router = APIRouter(prefix="/api/v1/profile", tags=["profile"])
+
+@router.get("/notifications")
+async def get_notifications():
+    return {"notifications": [], "unread": 0}