feat(chart): add a logarithmic y axis per pen (#72)

[mrcsin]

Problem

Pressure spans several decades and shares a screen with pens that do not; on a linear axis one of them
is unreadable. PenScaleSettings.IsLogarithmic existed in the model but nothing set it and the render
ignored it.

Change

• Log axis at the render edge. Core keeps data units. ChartAxisBinder sets decade limits and swaps
  in a LogTickGenerator; EnvelopeLine projects through log10; the generator is the axis type's one
  home and switches under Plot.Sync. LogAxis.Ticks picks decades, 1-2-5 mantissas or linear steps,
  bounded per call so no range can hang the render thread. Non-positive samples, and positive ones
  under the axis minimum, are pinned 2 px above the bottom; readouts show the true value. Major labels
  use the pen's mask and are demoted when the mask cannot show them.
• Stored start value. semiplot_tags.log_scale_on_start (SemiBase v0.5.0) reaches
  Pen.LogScaleOnStart and PenScaleSettings.InitialFor; the pen editor edits it as «Начальная шкала,
  логарифмическая». A changed stored value never changes a chart already open; Restore initial scale
  brings it back.
• Axis scale panel. «Логарифмическая шкала» switches the type for the session. The Apply button is
  gone: the bound pair is written when focus leaves both fields, on Enter, on a press on the panel's
  empty area or on a dismiss, and the panel stays open; Escape writes nothing. The box writes a pending
  pair before switching on, so "type 1, tick" works in one pass.
• Bench. Pressure 01 is a vacuum pen: mbar, 1e-6..1e-1, mask 0.0E+0, logarithmic on start.
• Docs in docs/architecture, AGENTS.md and readme.md; both plans move to docs/plans/completed/.

Closes #72

Verification

• SemiPlot.Tests.Unit 1800/1800, including LogAxisRenderTests (the 1e-4 plateau at the plot's
  middle, a zero plateau 2 px above the frame), LogAxisTests (tick families, degenerate and
  float-noise ranges in bounded time) and the axis scale panel's view tests.
• Container tests (PenCatalogueEditorTests, PostgresCatalogReadTests, TagCatalogWriterTests)
  against SemiBase v0.5.0.
• Manual test on the demo stand: the stored flag is written and read at start, the panel flows work.

Per-task commits before collapse

3973b7f docs(plans): record the axis panel run and checks
a293213 refactor(chart): drop the axis scale panel summary
c715cd1 refactor(chart): tidy the axis scale panel
9a3b655 feat(chart): use industry wording for the log scale
efaadc4 docs(chart): describe panel focus and toggle order
7b8546e refactor(chart): slim the axis scale panel model
d2636f0 fix(chart): keep Escape after an empty-area press
7ece9ba docs(plans): verify axis panel acceptance checks
fa996bc docs(chart): describe axis bound commit on focus
ec67e6a feat(chart): name the log10 base in the scale texts
6e10c39 feat(chart): end the axis bound edit on focus loss
a32abc9 feat(chart): commit axis bounds without apply
2b17eba docs(plans): add axis panel commit-on-focus plan
d9add3e docs(repo): drop the start-value note from the readme
9a76654 docs(plans): record the log10 run and its checks
1c33ec4 docs(chart): point log axis comments at the docs
a193f2d docs(chart): state non-finite pair, rewrap log docs
abb84ec test(chart): share log test helpers and fill gaps
82d51f6 refactor(bench): move the log walk into SyntheticValueWalk
9fa6353 refactor(chart): give each log axis rule one home
8c0beac fix(chart): default a non-finite manual scale pair
937e37e fix(chart): bound log minor tick loops
7a3ecd3 docs(chart): state SemiBase floor and open items
13c389f fix(pens): fit the log column and its message
a9d1c0b fix(chart): harden log labels, floor and padding
06cc170 docs(chart): document the log10 y axis
2537a5d test(chart): drop scale pair names from log test
43013c4 feat(bench): seed a decade-spanning log pen
f51174e feat(pens): edit log_scale_on_start in the pen editor
d88fad8 feat(chart): switch the log axis in the scale panel
5e1f8cc feat(chart): render the log10 y axis
ac6c0c1 feat(pens): read and write log_scale_on_start
b4e74ae feat(chart): add log10 projection and tick choice
16399be refactor(pens): suffix the start scale pair _on_start  (shipped as #112)