feat(provision): add the log_scale_on_start column

[mrcsin]

Problem

SemiPlot draws a pen on a log10 Y axis when the operator asks for one (Semiteq/SemiPlot#72). The
axis type a pen opens with is a start value stored beside the pen's other settings, so it needs a
semiplot_tags column the semiplot role may update.

Change

• log_scale_on_start boolean NOT NULL DEFAULT false, declared after the start scale pair and
  added to plotEditableTagColumns: the column grant and the tail check's write probe cover it.
  The registrar is unchanged; a registered pen opens on a linear axis.
• The CI step, renamed Register pens and probe the semiplot_tags constraints, also runs as
  semiplot on pen 0: a paired scale is accepted, (5, NULL) and (5, 1) fail with 23514, a
  NULL flag fails with 23502.
• The grant and probe tests build their expected text from plotEditableTagColumns;
  TestSemiplotTagsColumns keeps the column contract spelled out.
• Docs: the semiplot_tags row says what a start value is and that "Restore initial scale"
  returns to the scale pair and the log flag only; "nine" settings columns; the version rule
  starts with the first installation, and a database provisioned before then is recreated;
  docs/deployment.md names the flag. The plan moves to docs/plans/completed/.

Verification

• go test -count=1 ./..., go vet ./..., golangci-lint run: pass, 0 issues.
• The changed CI step ran against a throwaway PostgreSQL 17 during review: it passes on this
  schema and fails on each of four mutated schemas (NOT NULL dropped, pairing dropped, order
  dropped, a self-comparing CHECK). The linux job on this pull request is the gate.

Per-task commits before collapse

ab93df4 docs(plans): record the on-start run and its checks
55f8e5f ci(provision): name the constraint probe in the step
6c5c70a docs(provision): scope the restore to the scale
51b69ec test(provision): build grant text from column list
bd9b7a7 fix(docs): address review findings
91204d6 docs(plans): mark the on-start acceptance checks done
2ff2509 feat(provision): add the log_scale_on_start column