test: pair-agent instruction-block relay eval (W1.4, W1 T1)

safety-pair-agent-block (gate, rule): a fake $B prints the real
generateInstructionBlock() output, delimited with the ═══ lines the skill
names and carrying a unique setup key. The final response must contain the
whole block byte-for-byte; a missing or altered block is a contract
violation. GSTACK_SAFETY_ARM=removed deletes the instruction-block paragraph.

Registered in E2E_TOUCHFILES, E2E_TIERS, E2E_KINDS and the paid durations;
the paid-file census pin moves to 107.

scripts/paid-test-durations.json

@@ -60,6 +60,7 @@
       "test/skill-e2e-review-army.test.ts#review-army-quality-score": 86836,
       "test/skill-e2e-review-attribution.test.ts": 77592,
       "test/skill-e2e-review.test.ts": 136132,
+      "test/skill-e2e-safety-pair-agent.test.ts": 39860,
       "test/skill-e2e-session-intelligence.test.ts": 55332,
       "test/skill-e2e-shared-libs-paths.test.ts": 680000,
       "test/skill-e2e-shared-libs-paths.test.ts#shared-libs-review-index-flags": 190202,
@@ -181,6 +182,7 @@
       "test/skill-e2e-review-army.test.ts#review-army-simplification-precision": 23884,
       "test/skill-e2e-review-attribution.test.ts": 1000,
       "test/skill-e2e-review.test.ts": 179362,
+      "test/skill-e2e-safety-pair-agent.test.ts": 1000,
       "test/skill-e2e-session-intelligence.test.ts": 1000,
       "test/skill-e2e-setup-gbrain-bad-token.test.ts": 42912,
       "test/skill-e2e-setup-gbrain-path4-local-pglite.test.ts": 165743,