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/prober/tcpfp.py

@@ -15,6 +15,8 @@ import hashlib
 import random
 from typing import Any
 
+from decnet.telemetry import traced as _traced
+
 # Lazy-import scapy to avoid breaking non-root usage of HASSH/JARM.
 # The actual import happens inside functions that need it.
 
@@ -36,6 +38,7 @@ _OPT_CODES: dict[str, str] = {
 
 # ─── Packet construction ───────────────────────────────────────────────────
 
+@_traced("prober.tcpfp_send_syn")
 def _send_syn(
     host: str,
     port: int,
@@ -196,6 +199,7 @@ def _compute_fingerprint(fields: dict[str, Any]) -> tuple[str, str]:
 
 # ─── Public API ─────────────────────────────────────────────────────────────
 
+@_traced("prober.tcp_fingerprint")
 def tcp_fingerprint(
     host: str,
     port: int,