Clean up dead demos and restructure directory layout

Phase 1 - Remove dead/duplicate content:
- Delete demos/samples_java/ (incomplete Java demo)
- Delete demos/shared/chatbot_ui/ (replaced by AnythingLLM)
- Delete demos/shared/grafana/, prometheus/, logfire/, honeycomb/, signoz/
  (legacy observability stacks; only jaeger is retained)
- Delete variant docker-compose files (honeycomb, logfire, signoz, jaeger)
- Delete demos/use_cases/spotify_bearer_auth/run_demo.sh (stale script)

Phase 2 - Restructure into semantic categories:
- getting_started/  : weather_forecast, llm_gateway
- agent_orchestration/ : travel_agents, multi_agent_crewai_langchain
- llm_routing/       : model_alias_routing, preference_based_routing, claude_code_router
- filter_chains/     : http_filter, mcp_filter
- integrations/      : ollama, spotify_bearer_auth
- advanced/          : model_choice_test_harness, multi_turn_rag,
                       currency_exchange, stock_quote

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

demos/samples_python/weather_forecast/main.py

@@ -1,94 +0,0 @@
-import json
-import os
-import random
-from fastapi import FastAPI, Response
-from datetime import datetime, date, timedelta, timezone
-import logging
-from pydantic import BaseModel
-from opentelemetry import trace
-from opentelemetry.sdk.trace import TracerProvider
-from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
-from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter
-from opentelemetry.sdk.trace.export import BatchSpanProcessor
-from opentelemetry.sdk.resources import Resource
-
-
-resource = Resource.create(
-    {
-        "service.name": "weather-forecast-service",
-    }
-)
-
-# Initialize the tracer provider
-trace.set_tracer_provider(TracerProvider(resource=resource))
-tracer = trace.get_tracer(__name__)
-
-logger = logging.getLogger("uvicorn.error")
-logger.setLevel(logging.INFO)
-
-app = FastAPI()
-FastAPIInstrumentor().instrument_app(app)
-
-# Configure the OTLP exporter (Jaeger, Zipkin, etc.)
-otlp_exporter = OTLPSpanExporter(
-    endpoint=os.getenv("OLTP_HOST", "http://localhost:4317")
-)
-trace.get_tracer_provider().add_span_processor(BatchSpanProcessor(otlp_exporter))
-
-
-@app.get("/healthz")
-async def healthz():
-    return {"status": "ok"}
-
-
-class WeatherRequest(BaseModel):
-    location: str
-    days: int = 7
-    units: str = "Farenheit"
-
-
-@app.post("/weather")
-async def weather(req: WeatherRequest, res: Response):
-    weather_forecast = {
-        "location": req.location,
-        "temperature": [],
-        "units": req.units,
-    }
-    for i in range(req.days):
-        min_temp = random.randrange(50, 90)
-        max_temp = random.randrange(min_temp + 5, min_temp + 20)
-        if req.units.lower() == "celsius" or req.units.lower() == "c":
-            min_temp = (min_temp - 32) * 5.0 / 9.0
-            max_temp = (max_temp - 32) * 5.0 / 9.0
-        weather_forecast["temperature"].append(
-            {
-                "date": str(date.today() + timedelta(days=i)),
-                "temperature": {"min": min_temp, "max": max_temp},
-                "units": req.units,
-                "query_time": str(datetime.now(timezone.utc)),
-            }
-        )
-
-    return weather_forecast
-
-
-class DefaultTargetRequest(BaseModel):
-    messages: list = []
-
-
-@app.post("/default_target")
-async def default_target(req: DefaultTargetRequest, res: Response):
-    logger.info(f"Received messages: {req.messages}")
-    resp = {
-        "choices": [
-            {
-                "message": {
-                    "role": "assistant",
-                    "content": "I can help you with weather forecast",
-                },
-            }
-        ],
-        "model": "api_server",
-    }
-    logger.info(f"sending response: {json.dumps(resp)}")
-    return resp