ci: simplify DNS/SCI PR summaries and scope policy smart SCI

[MaurUppi]

Summary

• DNS Benchmark Compare: keep full artifact report, but PR bot comment now posts concise summary only (before/after + suite status + overall)
• Policy Smart SCI: restrict execution to policy-smart head branches on pull requests
• Policy Smart SCI: keep/update a single PR comment with concise summary (scope + overall + per-job status)

Why

• Current benchmark bot comment is too verbose for review
• SCI workflow should be scoped to policy-smart branch verification only

[github-actions]

Policy Smart SCI Summary

• Scope: feat/policy-smart -> main
• Overall: pass (3/3 passed)
• Workflow run: https://github.com/MaurUppi/dae/actions/runs/22400806997

Job Status

• ✅ SCI-1 Strategy Correctness: success
• ✅ SCI-2 TCP Retry Semantics: success
• ✅ SCI-3 Concurrency Race: success

[github-actions]

DNS Benchmark Compare Summary

• Before (base): origin/main
• After (head): 517760075c9173db046d6abac9ffe26273347962
• Base strategy: merge-base
• Suite profile: dns-module
• Overall: pass (5/5 passed)
• Workflow run: https://github.com/MaurUppi/dae/actions/runs/22400806967
• Full report artifact: dns-benchmark-compare-22400806967

Suite Status

• ✅ component_upstream_hotpath: pass
• ✅ control_cache_hotpath: pass
• ✅ control_cache_structures: pass
• ✅ control_core_flow: pass
• ✅ control_singleflight_scale: pass

Suite Delta (time/op geomean)

• component_upstream_hotpath: 6.370n -> 6.059n (Δ -4.89%)
• control_cache_hotpath: 12.86n -> 12.92n (Δ +0.45%)
• control_cache_structures: 43.42n -> 43.45n (Δ +0.08%)
• control_core_flow: 241.4n -> 241.7n (Δ +0.13%)
• control_singleflight_scale: 113.5µ -> 113.4µ (Δ -0.09%)