Polar Filament: add 17 colors and 5 products

[hochhause]

Adds 17 colors and 5 product entries to the existing filaments/polarfilament.json, all as additions.

Part of a migration of the Open Filament Database
(MIT licensed) into SpoolmanDB, one manufacturer per PR. The text below is the same on
every one of them.

Source

• OFD brand page: https://openfilamentdatabase.org/brands/polar_filament
• Manufacturer site: https://polarfilament.com
• (OFD records no data-sheet URL for this brand)

OFD collects its values from manufacturer product pages and technical data sheets.

Nothing here is AI-generated. The conversion is a field-mapping script with no
inference step: where OFD has no value, the field is omitted rather than filled. Density,
hex codes, temperature ranges and spool weights are carried across verbatim or not at all.
Script: https://gist.github.com/hochhause/f40c65a020c7bfd5a119b904b7558150

Existing entries are never edited

Where SpoolmanDB already has a group for a product, new colors go into that group —
including where its name predates the current naming rules (eSUN's PLA-Basic, for
instance). Creating a correctly-named parallel group would leave two entries for one
product, which seemed worse than an inconsistent name. Existing fields, names and colors
are untouched; every diff is additions only. Say the word if you would rather have the
rename and I will split them.

Where a color is sold in a spool size the existing group does not list, it cannot join
that group without inventing combinations, so it becomes a sibling entry under the same
name with the correct sizes — one product, two spool sizes.

What was left out, and how to get it back

Three kinds of color are withheld, on the principle that a missing color is cheaper to
fix than a duplicate:

• Already present — identical hex in the matching group. Your value stands.
• Name clashes — same color name as an existing entry but a different hex. Because
  name expands {color_name}, both would resolve to the same final product name and
  differ only by swatch. Correcting an existing hex is a separate question this PR does
  not try to answer.
• Within RGB distance 10 of an existing color under a different name — the same shade
  renamed or resampled, which is a judgement call about product identity.

Spool sizes are limited to 250 g, 500 g, 750 g, 1 kg, 1.1 kg, 2 kg, 3 kg, 5 kg and
10 kg. Everything else in OFD's long tail is left out: 9 kg, 8 kg, 4.5 kg, 2.5 kg,
2.3 kg, 850 g, 800 g and a scatter of rarer ones, including a few that look like a gross
weight rather than a filament weight (4310 g, 5310 g, 4010 g). A color sold only in an
excluded size is left out entirely rather than attached to a size it is not sold in.

Across the whole migration that is 892 colors already present, 1158 name
clashes, 46 near-identical shades and 227 colors held back on spool size.

If you want any of it — a size, a clash, a near-shade, for this manufacturer or
globally — just ask and I will add it. It is one line in the converter, not a re-run
of the research.

Normalisation applied

• Material taken out of the name. PLA-Matte → material: PLA,
  name: "Matte {color_name}", following the PETG-Tough example in CONTRIBUTING.
  Compound tokens that really are a different plastic (PLA-CF, PA6-GF25, TPU-95A,
  PC+ABS) move into material instead.
• Manufacturer removed from the name wherever OFD repeated it.
• Sizes split so combinations stay real. Since the build multiplies
  weights × diameters × colors, colors are grouped by the size set they are actually sold
  in and each group split so the cross product contains only combinations that exist.
  Verified against the source: 20,709 real (color, diameter, weight) rows, 0 fabricated,
  0 lost.
• Where OFD records no size at all for a color, 1.75 mm / 1 kg is assumed. That is an
  assumption, not a source value, and it affects 13 records in the entire database.

scripts/lint_filaments.py reports no new errors against this file.

Fields left empty

extruder_temp / bed_temp — OFD stores a min/max range, mapped to extruder_temp_range
and bed_temp_range. The single-value fields have no source value, so they are omitted
rather than derived from a midpoint. spool_weight and spool_type are present only
where OFD records them.

[github-actions]

Catalog preview

This PR would add 17 entries to Spoolman, listed below as they will appear to users.

Please check this against the manufacturer's product catalog. Every combination of weight, diameter and colour is generated automatically, so a spool size or diameter that only exists for some colours will show up here as products that aren't really sold. If you see any, split the filament into separate objects so only real combinations are produced.

• Polar Filament - ASA Gray · 1.75 mm · 1000 g · spool type not set
• Polar Filament - PA12 Natural Nylon · 1.75 mm · 1000 g · spool type not set
• Polar Filament - PHA Biodegradable Black · 1.75 mm · 1000 g · spool type not set
• Polar Filament - PHA Biodegradable Natural · 1.75 mm · 1000 g · spool type not set
• Polar Filament - PLA Color Changing Blue · 1.75 mm · 1000 g · cardboard spool (190 g tare)
• Polar Filament - PLA Dijon Yellow · 1.75 mm · 1000 g · cardboard spool (190 g tare)
• Polar Filament - PLA Lavender · 1.75 mm · 1000 g · cardboard spool (190 g tare)
• Polar Filament - PLA Nuclear Green · 1.75 mm · 1000 g · cardboard spool (190 g tare)
• Polar Filament - PLA Spaceship Steel · 1.75 mm · 1000 g · cardboard spool (190 g tare)
• Polar Filament - TPU Biodegradable Flexible 95A Soft Black · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU Biodegradable Flexible 95A Soft Natural · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Candy Red Flexible · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Classic Black Flexible · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Light Blue Flexible · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Natural Flexible · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Shamrock Flexible · 1.75 mm · 1000 g · spool type not set
• Polar Filament - TPU-60D Vivid Orange Flexible · 1.75 mm · 1000 g · spool type not set