fix(data): repair 18 fabricated placeholder RAM values in PDA records

Post-dedup scan of all 112 pda records for the fabricated-default fingerprint
(one fake-precise value repeated across many unrelated devices), independent of
whether a record had a duplicate twin.

Clusters found:
- ram_gb=1 on 83 of 112 records. Definitively fabricated: no PDA from 2000-2011
  had 1 GB of RAM (Dell Axim X5 = 32/64 MB, Palm IIIc = 8 MB, etc.). This is the
  Kaggle/phonedb bulk-import placeholder.
- battery_mah=1500 on 33 records (mostly the classic Palm line), and
  weight_g=190 on 9 - see "left as-is" below.

Fixed 18 ram_gb=1 values to the real, sourced figure (ram_gb is a required field,
so these are repaired to a cited value, not nulled). No value invented - each
comes from an authoritative source added to source_urls:

- 13 Dell Axim (Wikipedia Dell Axim specification table): X5/X3/X30 low-end
  ("Basic") = 32 MB = 0.03125; every other Axim model (X3/X3i Advanced, X30
  Advanced, and the whole X50/X51 line) = 64 MB = 0.0625.
- 5 Fujitsu-Siemens Pocket Loox N520/N560 = 64 MB = 0.0625 (Fujitsu N520 user
  manual + clubic N560 launch spec).

Left as-is, documented rather than guessed or nulled:
- Classic Palm line (Palm IIIc/IIIxe/VIIx = 8 MB, m100 = 2 MB, m105/m125/m130/
  m500/m505 = 8 MB, m515 = 16 MB, Tungsten/Zire/Treo/Centro, etc.): their real
  RAM is below the schema's ram_gb>=0.016 (16 MB) floor, so it is not
  representable - almost certainly why they were stamped with the ram=1
  placeholder in the first place. Can't set the real value (fails validate),
  can't null a required field. Reported on #296.
- The remaining ram_gb=1 records (i-mate PDA phones, HP iPAQ Glisten, Mitac Mio
  728, later Palm Treo/webOS) need individual per-device sourcing; left documented.
- battery_mah=1500: the classic Palms ran on AAA/AA cells (m100/m105/m125) or
  small internal Li-ions - clearly not a uniform 1500 mAh - but there is no clean
  per-device mAh to cite without inventing, and the field is required (can't null).
  Reported on #296.
- ppi=114 (26 records) and the 3.5"/240x320 combo are NOT fabricated: 240x320
  QVGA on a 3.5" panel really is ~114 ppi, legitimately shared by that whole
  common screen class. weight_g=190 (9) is real chassis-sharing (iPAQ h63xx
  family, i-mate HTC rebrands). Left untouched.

Both gates pass: `python -m app.validate` and `integrity_check.py <data> --strict`
(0 hard anomalies).

Refs #296

Author: Seungpyo1007

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

@@ -4,13 +4,14 @@
   "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",
   "verified": true,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=80"
+    "https://phonedb.net/index.php?m=device&id=80",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

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

@@ -4,13 +4,14 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa250",
   "release_date": "2002-11-01",
-  "ram_gb": 1,
+  "ram_gb": 0.03125,
   "battery_mah": 1440,
   "weight_g": 196.0,
   "os": "Feature phone",
   "verified": true,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=79"
+    "https://phonedb.net/index.php?m=device&id=79",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

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": 0.03125,
   "battery_mah": 950,
   "weight_g": 137.0,
   "os": "Windows Mobile",

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

@@ -4,13 +4,14 @@
   "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",
   "verified": true,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=83"
+    "https://phonedb.net/index.php?m=device&id=83",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

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

@@ -4,13 +4,14 @@
   "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",
   "verified": false,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=86"
+    "https://phonedb.net/index.php?m=device&id=86",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

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

@@ -4,13 +4,14 @@
   "brand": "dell",
   "soc": "intel-xscale-pxa270",
   "release_date": "2004-05-01",
-  "ram_gb": 1,
+  "ram_gb": 0.03125,
   "battery_mah": 950,
   "weight_g": 134.4,
   "os": "Windows Mobile",
   "verified": false,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=85"
+    "https://phonedb.net/index.php?m=device&id=85",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

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

@@ -4,13 +4,14 @@
   "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",
   "verified": false,
   "source_urls": [
-    "https://phonedb.net/index.php?m=device&id=130"
+    "https://phonedb.net/index.php?m=device&id=130",
+    "https://en.wikipedia.org/wiki/Dell_Axim#Specifications"
   ],
   "display": {
     "size_inch": 3.5,

data/pda/dell/2004/dell-axim-x50v/dell-axim-x50v.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",