docs(adr-001): streaming example using event_stream_iter

[ruvnet]

Summary

Companion to `event_driven_anomaly.rs` (PR #33/#35). The earlier example called the per-event primitives directly; this one uses the iterator adapter from PR #45 and composes it with stdlib's iterator chain — the native Rust pattern RuView / Cognitum / Ruflo would adopt.

Demonstrates

• One event stream → one iterator chain → reports.
• Coherence-gated skip on tiny deltas (latency 0).
• `PlanBudget` cap on cumulative ops; iterator ends gracefully when exhausted.
• Per-event latency tracked by the iterator.

Sample output (10-event stream, budget=4 SubLinear ops)

```
event # status latency_us top-anomaly
─────────────────────────────────────────────
0 Solved 73 row 7
1 Skipped 0 row —
2 Solved 43 row 22
3 Skipped 0 row —
4 Solved 41 row 40
5 Solved 42 row 51
6 Skipped 0 row —
7 BudgetRefused 0 row —

Summary: 4 solved, 3 skipped by gate, 1 budget-refused
```

Architecture line fully realised

• streaming surface — stdlib iterator composition
• per-event — SubLinear (auto-tuned closure + Neumann)
• coherence gate — O(|δ|) skip-on-tiny-delta
• budget gate — O(1) per consume, ends iterator on refuse

Test plan

• `cargo run --release --example event_stream_processing` produces the expected gated/budgeted output
• Full CI

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