fix(atlas): address PR #100 review — star_type audit, data quality fixes

- Fix star_type/spectral_class mismatches across 36 proposals
- Differentiate GJ1002 copy-paste planets (c-g had identical params)
- Fix GJ880 malformed spectral_class (M2: → M2V) and Leirvik station pop
- Fix GJ3325 malformed spectral_class (K: → K)
- Correct white dwarf star_type (GJ1221, GJ3991 → D)
- Correct "unusual" star_type (GJ3877, GJ661A → K)
- Delete tooling/atlas-helpers.sh (superseded by clean scripts on main)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/atlas/proposals/GJ702B.json

@@ -1,7 +1,7 @@
 {
   "system_id": "GJ 702B",
   "proper_name": "Prometheus",
-  "star_type": "G",
+  "star_type": "K",
   "spectral_class": "K5 Ve",
   "wiki_data": {
     "habitable_count": 0,
@@ -41,7 +41,7 @@
       "inhabited": false,
       "population": 0,
       "mass_class": "terrestrial",
-      "surface_gravity": 0.60,
+      "surface_gravity": 0.6,
       "orbital_period_days": 55,
       "rotation_period_hours": 1320,
       "atmosphere": "toxic",
@@ -90,7 +90,7 @@
       "economic_role": null,
       "settlement_pattern": null,
       "industrial_corridor": null,
-      "notes": "habitable-zone, breathable — Prometheus chose not to colonize"
+      "notes": "habitable-zone, breathable \u2014 Prometheus chose not to colonize"
     },
     {
       "body_id": "GJ702Bf",
@@ -101,7 +101,7 @@
       "inhabited": false,
       "population": 0,
       "mass_class": "terrestrial",
-      "surface_gravity": 0.50,
+      "surface_gravity": 0.5,
       "orbital_period_days": 500,
       "rotation_period_hours": 18.0,
       "atmosphere": "thin",