docs: streamline tone across reference docs

Tone pass across the non-tutorial markdown — README, PROOFS,
ARCHITECTURE, BENCHMARKS, COMPLIANCE, FAQ, MES_INTEROP, SECURITY,
and interop/README.  Three patterns came out:

- Bug-history war stories ("Past interop sweeps surfaced…",
  "What these harnesses caught: 1. Strict U-width parsing…").
- Chat-with-reader framing ("Don't skip TLS unless…", "Treat as a
  punch list", "If you're running in a pod…", "Misconfiguration
  incidents drop dramatically").
- Self-referential narration ("we ship", "our codec", "the
  codebase's most-tested layer", "three orders of magnitude above
  fab load", "the gift that keeps giving").

README also drops the standalone ThreadSanitizer subsection under
Build details (now a single line under the new Testing section).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docs/BENCHMARKS.md

@@ -2,9 +2,8 @@
 
 Numbers from `build/secs_bench --requests 20000 --concurrency 16` on
 Docker / Ubuntu 24.04 inside Docker Desktop on macOS (M-series), single
-io_context thread.  Treat as **rough envelope for capacity planning**,
-not lab-grade benchmarks; re-run on your target hardware before
-sizing pods or VMs.
+io_context thread.  A rough capacity-planning envelope, not a
+lab-grade benchmark — re-run on target hardware before sizing.
 
 ## Round-trip throughput / latency
 
@@ -14,10 +13,8 @@ sizing pods or VMs.
 | S1F3/F4 (32 SVIDs)               |   20000 |    0.25 |     ~79000 |     165 |     186 |     260 |
 | S6F11 push (W=0)                 |   20000 |    0.03 |    ~572000 |     n/a |     n/a |     n/a |
 
-**Read the table this way.** A real fab tool needs to handle tens to a
-few hundred S6F11 events/second sustained.  We're three orders of
-magnitude above that on the push path, two orders above on synchronous
-round-trips.  Throughput is not the bottleneck; latency tail under
+A real fab tool sustains tens to a few hundred S6F11 events/second.
+Throughput is not the bottleneck on this stack; latency tail under
 contention is.
 
 ## Memory footprint
@@ -50,8 +47,7 @@ docker compose run --rm builder /app/build/secs_bench \
     --store-pairs 10000
 ```
 
-Output is markdown — pipe to a file and commit it to your CI so
-regressions show up as diffs.
+Output is markdown.
 
 ## What this does NOT measure