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>

interop/README.md

@@ -1,13 +1,11 @@
 # External cross-validation harnesses
 
-Every harness in this directory exists so a reviewer doesn't have to
-take our word for it.  Each one validates our C++ codec / framing /
-dispatch against an **independent third-party implementation** that
-read the SEMI standards without talking to us.
+Each harness in this directory validates the C++ codec, framing, and
+dispatch against an **independent third-party implementation** of
+the same SEMI standards.
 
-See [`../docs/VERIFICATION.md`](../docs/VERIFICATION.md) for the full
-test plan and the honest accounting of which proofs are external vs
-internal.
+See [`../docs/VERIFICATION.md`](../docs/VERIFICATION.md) for the
+internal-vs-external breakdown across all validators.
 
 ## What's here
 
@@ -83,44 +81,11 @@ Drops the host link mid-flight, kills the server, restarts it, and
 asserts the spooled S5F1 / S6F11 frames drain to the host on
 reconnect.
 
-## What these harnesses caught
-
-Real bugs surfaced during interop development (now fixed):
-
-1. **Strict U-width parsing rejected U1-encoded identifiers.**  SEMI
-   E5 declares DATAID, RPTID, VID, CEID, ALID, EXID etc. as
-   `U1 | U2 | U4 | U8`; secsgem-py picks the smallest width that
-   fits.  Our scalar accessors were strict.  Now lenient with
-   range-checked downcasts (`messages_helpers.hpp::any_unsigned_first`).
-
-2. **PPBODY rejected when sent as ASCII.**  SEMI allows PPBODY to be
-   `ASCII | Binary | List`; secsgem-py defaults to ASCII.  Added the
-   `BINARY_OR_ASCII` codegen type and the `as_text_or_binary`
-   accessor.
-
-3. **Missing S1F23 / S1F24 (Collection Event Namelist).**  Added the
-   wire schema, the `vids_for(ceid)` accessor, and the dispatch
-   handler.
-
-4. **Missing S10F3 handler (host→equipment Terminal Display).**  Our
-   server only registered S10F1; per SEMI E5 §13 those are opposite
-   directions.  Added the missing dispatch.
-
-5. **TSan use-after-free in `act_exception_complete`** (test code,
-   not library): held a pointer across `fire_internal(RecoveryComplete)`
-   which deletes the entry.  Found by the ThreadSanitizer lane on
-   first run.
-
-The C++ test suite stayed green through every one of these fixes —
-the changes were purely permissive widenings or additive features,
-no existing behaviour broke.
-
 ## When to add a new validator
 
-A new third-party SECS implementation, or a new dissector, or a new
-fuzzer target — anything that exercises our wire surface from an
-angle the existing five don't cover — is worth adding.  The pattern
-is consistent:
+A new third-party SECS implementation, dissector, or fuzzer target
+that exercises the wire surface from an angle the existing five
+don't cover is worth adding.  The pattern is consistent:
 
 1. New script / harness lives here (or a sidecar Docker context for
    non-Python validators).
@@ -129,6 +94,5 @@ is consistent:
 4. Surfaced in [`../docs/PROOFS.md`](../docs/PROOFS.md) if it adds a
    meaningful new dimension.
 
-Bug reports from a new validator → file at
-`raphael@maenle.net` with the wire trace, the validator's output,
-and the equipment YAML so we can reproduce.
+Bug reports from a new validator → file at `raphael@maenle.net`
+with the wire trace, the validator's output, and the equipment YAML.