audit: cycle 0101 tidy (drift-clean after one ledger alignment)

Architect review of 8814e295..HEAD. What holds: the cosmetic-only claim is
verified (every -/+ pair in the code diff is a string literal; no exit(),
channel, or control-flow byte moved; the C14 usage=2/runtime=1 partition
preserved at every touched site); grep gates exact (zero lowercase usage:
literals, 11 'Usage: aura' source lines = 10 edited + the pre-conforming
run_args_from); fieldtests corpus and refusal diagnostics byte-identical.
The recorded spec deviation (3 additive house-style pins) strengthens
coverage over a real pin gap and is decision-logged on the issue.

Regression: cargo build rc=0, cargo test --workspace rc=0 (cli_run 133
passed / 0 failed), clippy -D warnings rc=0, doc build rc=0. No baselines
exist to move, so nothing to ratify.

Drift resolved in this commit: the C14 ledger note still described the
casing normalization as deferred after #179 landed - rewritten to record
the landed house style (usage lines 'Usage: aura <verb> ...', refusal
diagnostics deliberately unprefixed).

Ephemeral cycle artifacts removed per convention: spec 0101, plan 0101.

refs #179

docs/design/INDEX.md

@@ -1087,7 +1087,9 @@ needed environment / recorded state is missing, or bad piped stdin data. The fou
 dual-grammar subcommands (run/sweep/walkforward/mc) keep both grammars under one
 token via an optional `[blueprint]` positional + a post-parse `is_file()`
 dispatch; the execution layer is unchanged (arg-plumbing via thin `*_from`
-adapters). Error-message casing normalization was deferred (#179); the
+adapters). Error-message casing is normalized to the clap house style —
+every hand-rolled usage line reads `Usage: aura <verb> …` (#179, cycle 0101);
+refusal diagnostics stay unprefixed (diagnostics are not usage lines). The
 machine-first help surface (JSON/manifest help, stdin op-scripts) stays on the
 #157/C21 track, not this cycle (settled as human/GNU convention compliance).