Fix final-review findings: unit-label baseline, sqrt minor-tick math, dead code, edge cases

- Unit label was vertical-centered on a box derived from a baseline
  coordinate, shifting it 3.34mm too low and making the generated
  deliverables inconsistent with E440-Scale_template.svg. UNIT_Y is now
  used directly as the baseline; regenerated E440-Scale_paths.svg and
  E440-Scale_text.svg accordingly.
- sqrt scale's minor-tick angle formula double-applied the square-root
  mapping, badly misplacing minor ticks. Removed the special case so sqrt
  falls through to the already-correct generic value-interpolation branch.
  Corrected README's sqrt row (crowds toward the high end, not low).
- Removed dead code: unused _has_markup(), identity-transform wrapper and
  _UNIT_SCALE_X in _markup_unit_svg, unreachable max_val<=0 check,
  redundant math.isinf() in the minor-tick condition.
- Linear scale with min==max now raises ValueError like the other three
  mappings, instead of silently producing a degenerate dial.
- Form numeric parsing moved inside the try/except so bad input returns
  400 instead of crashing with 500.
- left_label/right_label now split on splitlines() to handle CRLF from
  browser textareas correctly.
- Formatting consistency: PIVOT_CIRCLE_R/R0 use :.5f like other constants;
  font_face indentation matches its sibling elements.
- LICENSE and CLAUDE.md: last M1730-Scale references and a doc inaccuracy
  about which labels are live text vs. outlined paths.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

LICENSE

@@ -208,7 +208,7 @@ If you develop a new program, and you want it to be of the greatest possible use
 
 To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively state the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
 
-     M1730-Scale
+     E440-Scale
      Copyright (C) 2026  adebaumann
 
      This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
@@ -221,7 +221,7 @@ Also add information on how to contact you by electronic and paper mail.
 
 If the program does terminal interaction, make it output a short notice like this when it starts in an interactive mode:
 
-     M1730-Scale  Copyright (C) 2026  adebaumann
+     E440-Scale  Copyright (C) 2026  adebaumann
      This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
      This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details.