chore(coverage): raise the coverage ratchet from 48.5% to 54.2%

The committed baseline had drifted well below reality: it still read 48.5%
while a full instrumented run measures 54.2%. A stale-low baseline makes the
gate meaningless — coverage could regress by more than 5 percentage points
and still pass.

Raising a ratchet is a deliberate act, not something to fold into an
unrelated fix, so it gets its own commit. The headroom was earned by tests
landed in #10946, #10947, #10948, #10949, #10956, #10967, #10968, #10970 and
#10975.

Measured with `make test-coverage` on this branch (the same instrumented run
`make test-coverage-baseline` uses: ginkgo over ./pkg and ./core plus the
in-process tests/e2e suite, --covermode=atomic, --coverpkg over core/... and
pkg/..., generated protobuf excluded). The run completed with exit 0 and zero
spec failures; the total was then written with the exact command the
test-coverage-baseline target uses:

  go tool cover -func=coverage/coverage.out \
    | awk '/^total:/{gsub(/%/,"",$NF); print $NF}' > coverage-baseline.txt

Verified afterwards with scripts/coverage-check.sh, which reports OK.

Note the measured figure includes the readiness specs added earlier on this
branch, so it is a demonstrated floor rather than an estimate.

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Assisted-by: Claude:claude-opus-4-8 [Claude Code]

Author: mudler

coverage-baseline.txt

@@ -1 +1 @@
-48.5
+54.2