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/jarm.py

@@ -8,7 +8,7 @@ fingerprint that identifies the TLS server implementation.
 
 Reference: https://github.com/salesforce/jarm
 
-No DECNET imports — this module is self-contained and testable in isolation.
+Only DECNET import is decnet.telemetry for tracing (zero-cost when disabled).
 """
 
 from __future__ import annotations
@@ -19,6 +19,8 @@ import struct
 import time
 from typing import Any
 
+from decnet.telemetry import traced as _traced
+
 # ─── Constants ────────────────────────────────────────────────────────────────
 
 JARM_EMPTY_HASH = "0" * 62
@@ -379,6 +381,7 @@ def _version_to_str(version: int) -> str:
 
 # ─── Probe sender ────────────────────────────────────────────────────────────
 
+@_traced("prober.jarm_send_probe")
 def _send_probe(host: str, port: int, hello: bytes, timeout: float = 5.0) -> bytes | None:
     """
     Open a TCP connection, send the ClientHello, and read the ServerHello.
@@ -471,6 +474,7 @@ def _compute_jarm(responses: list[str]) -> str:
 
 # ─── Public API ──────────────────────────────────────────────────────────────
 
+@_traced("prober.jarm_hash")
 def jarm_hash(host: str, port: int, timeout: float = 5.0) -> str:
     """
     Compute the JARM fingerprint for a TLS server.