Report: the clock, the renderer, and a minimum frame owned by the USB bridge

Brings the document up to the end of Experiment 4. Two rows on the progression table -
360 MHz and direct emission - plus the sections behind them, the corrected verifier, and
a summary that no longer says the target was missed. It is met: 3.74 ms from 16.99.

The two findings worth more than the number, and both are written up as findings rather
than as steps:

A 4x clock bought 2.6x. The grid walk reads 27 KB a frame at about six cycles a byte, so
it is bounded by L2MEM bandwidth and does not care how fast the core runs. Predicted
before the measurement.

The direct renderer measured SLOWER at first - less computation, a quarter of the bytes,
worse round trip - because the CH340 forwards a bulk IN packet only when the packet is
full, and a 21-byte frame does not fill 32. It waits about a millisecond for a timer.
So the frame has a minimum size and it belongs to the transport, not the terminal; the
emitter pads to it with repeated cursor positioning. The table of 21/49/81-byte frames is
in the report because the MINIMUM column is the tell: the small frame's floor was already
530 us below vaxis's, exactly the compute saved, and only the median was hostage.

Also corrected: the verifier section. It described hashing SGR parameters per cell, which
is a history rather than a state, and that version reported a difference on the die that
did not exist - a faster board split the same keystrokes across different frames and
reached the same colours by another route. The document now says what it does instead,
and why the from-scratch renderer could not have been verified without the fix.

Table 13, the ranked recommendations from Experiment 3, is kept as the prediction it was
with a note on what has since been applied and that row 3 - raise the line rate - was
abandoned. The threats section no longer states the link floor as a single number, since
the bridge's packet granularity is now part of it and is specific to this bridge.

Nine pages. Every figure still reads the raw per-trial CSVs, including the two new ones.

1 files changed, 64 insertions, 0 deletions

diff --git a/experiments/length-DirectEmit.csv b/experiments/length-DirectEmit.csv
new file mode 100644
index 0000000..f4fbd29
--- /dev/null
+++ b/experiments/length-DirectEmit.csv
@@ -0,0 +1,64 @@
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