ops(e2e): enable zone_detection — prerequisite for datamarking shadow validation

Stage 1.5 of the IS-060 PR-2 validation chain. PR #216 enabled
datamarking in shadow mode, but the first nightly cycle on top of
that change produced zero spotlighting findings — because
SecurityAnalysisConfig.zone_detection.enabled defaults to false, the
proxy never identifies Data zones, and datamarking has nothing to
transform.

Without zone_detection enabled, the chain looks like:

  request → forward upstream  (boundary tags applied, datamarking
                               sees no zones, transform is a no-op)

With zone_detection enabled:

  request → zone-detect → boundary-wrap → datamarking (shadow:
                                          compute + metrics, forward
                                          original bytes)

This PR enables zone_detection in the nightly fixture with the
default-permissive policy:
- mode: both (heuristic FSM + operator markers, operator wins on overlap)
- scan_instruction_zones: false (data zones only, the only candidates
                                  for marker substitution)

After this lands, re-trigger workflow_dispatch nightly. Expected
signal in `e2e_<date>.json`: `spotlighting_applied` Info findings
emitted per request that contains a detected Data zone (BIPIA-style
tables, code fences, HTML, JSON value extraction, markdown).

Refs: #214 (PR-2 implementation), #213 (PR-3 corpus, provides the
zones), #216 (shadow-mode prelude — incomplete without this).

Author: epappas

tests/e2e/fixtures/config-e2e-judge.yaml

@@ -54,6 +54,17 @@ health_check:
   timeout_ms: 5000
   retries: 3
 
+# IS-060 PR-1 zone detection — required for datamarking (PR-2) to have
+# Data zones to transform. Both heuristic and operator-declared zones
+# are honoured; instruction zones are skipped per the default policy
+# (data zones are the only candidates for marker substitution).
+security_analysis:
+  zone_detection:
+    enabled: true
+    mode: both
+    scan_instruction_zones: false
+
+
 # IS-060 — Boundary defense + datamarking transform.
 # Enabled in shadow mode for the first validation cycle: data zones are
 # wrapped with <llmtrace-boundary>...</llmtrace-boundary> tags AND the