feat: complete OTEL tracing across all services with pipeline bridge and docs

Extends tracing to every remaining module: all 23 API route handlers,
correlation engine, sniffer (fingerprint/p0f/syslog), prober (jarm/hassh/tcpfp),
profiler behavioral analysis, logging subsystem, engine, and mutator.

Bridges the ingester→SSE trace gap by persisting trace_id/span_id columns on
the logs table and creating OTEL span links in the SSE endpoint. Adds log-trace
correlation via _TraceContextFilter injecting otel_trace_id into Python LogRecords.

Includes development/docs/TRACING.md with full span reference (76 spans),
pipeline propagation architecture, quick start guide, and troubleshooting.

decnet/telemetry.py

@@ -64,7 +64,9 @@ def setup_tracing(app: Any) -> None:
         _init_provider()
         from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
         FastAPIInstrumentor.instrument_app(app)
-        log.info("FastAPI auto-instrumentation active")
+        from decnet.logging import enable_trace_context
+        enable_trace_context()
+        log.info("FastAPI auto-instrumentation active, log-trace correlation enabled")
     except Exception as exc:
         log.warning("OTEL setup failed — continuing without tracing: %s", exc)