fix(data): resolve 83 PDA placeholder ram_gb/os values

The PDA dedup follow-up flagged a systemic placeholder pattern in data/pda/:
nearly every clean record carried ram_gb=1 (a placeholder, not 1 GB) and many
Palm/Dell/MiTAC records carried os="Feature phone" for devices that actually
run Palm OS, webOS, or Windows Mobile.

Sourced the real values per device from each record's cited phonedb.net
datasheet (RAM Capacity + Platform fields); for the six kaggle-only records
without an in-record phonedb id, sourced from Wikipedia (Treo 180/270/600/650)
and imei24 (iPAQ Glisten, i-mate Pocket PC), added to source_urls.

- os: "Feature phone" -> "Palm OS" / "webOS" / "Windows Mobile" per device
  (50 records corrected; the Windows-Mobile Treos/Dell/Fujitsu-Siemens that were
  already correct kept their os).
- ram_gb: placeholder 1 -> true capacity, converted MiB/1024 to match the
  existing dataset convention (16->0.016, 32->0.032, 64->0.0625, 128->0.125,
  256->0.25, 512->0.5). variant.memory.ram_gb mirrored where present.

Left unresolved (documented, not invented): 12 pre-2003 Palm classics with
2-8 MiB RAM (m100/Zire = 2 MiB; IIIc/IIIxe/VIIx/m105/m125/m130/m500/m505/m515... )
— their true RAM is below the schema's ram_gb floor (0.016 GB = 16 MiB in
app/validate.py), so it cannot be represented without overstating it; their os
was still corrected to "Palm OS" and ram_gb left at the prior value rather than
writing a wrong in-range number.

Verified: python -m app.validate passes; integrity_check.py --strict reports no
hard anomalies.

Refs #296

Author: Seungpyo1007

data/pda/dell/2002/dell-axim-x5-advanced/dell-axim-x5-advanced.json

@@ -4,10 +4,10 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa250",
   "release_date": "2002-11-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 1440,
   "weight_g": 196.0,
-  "os": "Feature phone",
+  "os": "Windows Mobile",
   "verified": true,
   "source_urls": [
     "https://phonedb.net/index.php?m=device&id=80"

data/pda/dell/2002/dell-axim-x5-basic/dell-axim-x5-basic.json

@@ -4,10 +4,10 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa250",
   "release_date": "2002-11-01",
-  "ram_gb": 1,
+  "ram_gb": 0.032,
   "battery_mah": 1440,
   "weight_g": 196.0,
-  "os": "Feature phone",
+  "os": "Windows Mobile",
   "verified": true,
   "source_urls": [
     "https://phonedb.net/index.php?m=device&id=79"

data/pda/dell/2003/dell-axim-x3-advanced/dell-axim-x3-advanced.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa263",
   "release_date": "2003-09-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 950,
   "weight_g": 137.0,
   "os": "Windows Mobile",

data/pda/dell/2003/dell-axim-x3-basic/dell-axim-x3-basic.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa263",
   "release_date": "2003-09-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 950,
   "weight_g": 137.0,
   "os": "Windows Mobile",

data/pda/dell/2003/dell-axim-x3i/dell-axim-x3i.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa263",
   "release_date": "2003-09-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 950,
   "weight_g": 140.0,
   "os": "Windows Mobile",

data/pda/dell/2004/dell-axim-x30-advanced/dell-axim-x30-advanced.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-05-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 950,
   "weight_g": 139.0,
   "os": "Windows Mobile",

data/pda/dell/2004/dell-axim-x30-basic/dell-axim-x30-basic.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-05-01",
-  "ram_gb": 1,
+  "ram_gb": 0.032,
   "battery_mah": 950,
   "weight_g": 134.4,
   "os": "Windows Mobile",

data/pda/dell/2004/dell-axim-x30i/dell-axim-x30i.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-05-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 950,
   "weight_g": 139.0,
   "os": "Windows Mobile",

data/pda/dell/2004/dell-axim-x50-advanced/dell-axim-x50-advanced.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-10-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 1100,
   "weight_g": 167.0,
   "os": "Windows Mobile",

data/pda/dell/2004/dell-axim-x50-basic/dell-axim-x50-basic.json

@@ -4,7 +4,7 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-10-01",
-  "ram_gb": 1,
+  "ram_gb": 0.0625,
   "battery_mah": 1100,
   "weight_g": 167.0,
   "os": "Windows Mobile",