re: the section reader is a generic IDXD accessor; UNIT_MAX absence re-tested

Resolving the r4 string at every sub_82448AA0 / sub_824482D0 call site
gives 65 section names and 54 int keys (data/config-keys.txt) -- far
more than the 400-byte config.ini holds -- and BASE_INFO, SYSTEM,
MISSIONS and FONTS are all present as IDXD record keys on the disc.  So
it is a generic named-section accessor over the .tbl containers, not
"the INI reader" as I labelled it yesterday.

My first re-test was invalid: IDXD record keys are tag_hash, not
name_hash.  Scanning with name_hash returned 0 for STAGENN_UNIT_MAX and
0 for every control name too -- the control is what exposed it.

Redone with tag_hash: 7750/7750 entries parsed, 190782 records, 3496
distinct keys, controls BASE_INFO/SYSTEM/MISSIONS/FONTS found, and
STAGE01..33_UNIT_MAX -> 0 records.  With the literal search and
config.ini printed in full, the section exists nowhere on the disc, so
PLANE=200 / VESSEL=20 for every stage now rests on a controlled test.

Docs + one new artefact; ISL artefacts byte-identical.

docs/re/data/config-keys.txt

@@ -0,0 +1,129 @@
+# The named-section / int-key vocabulary the engine asks for
+
+Resolved by back-tracking the r4 string argument at every call site of
+sub_82448AA0 (find a named section/record) and sub_824482D0 (read an int).
+Only sites whose key is a literal addis/addi string are listed, so these are
+LOWER BOUNDS, not the complete set.
+
+## sub_82448AA0 -- named section / record  (65 distinct)
+     1  ACHIEVEMENTS_REQUIREMENTS
+     3  AUTO_SETTINGS
+     1  ArmsItem
+     1  ArmsItemFile
+    19  BASE_INFO
+     1  COMMON_RESOURCE
+     1  COMMON_XPR
+     1  CUSTOM_KEY_LOCATE
+     1  Camera
+     1  ControlTweak
+     4  CorrespondingTable
+     3  EPILOGUE_MOVIES
+     2  EnumCharacter
+     2  EnumUnit
+     1  EnumWeapon
+     1  Enumerate_ObjectiveMarkers
+     1  FILE
+     2  FILES
+     4  FONTS
+     2  FONT_SET
+     1  Faces
+     1  Files
+     1  GP_MAIN_GAME
+     2  GP_SCRIPT
+     1  Generic
+     3  IGNORE
+     2  LANGUAGE
+     4  LOCATE
+     2  LocalStringFiles
+     5  MISSIONS
+     1  MotionResource
+     1  Number
+     1  OFFSET
+     1  OPEN_PAK
+     1  Parameters
+     5  Path
+     2  PrefetchPaks
+     1  RADIO_WINDOW
+     1  Rendering
+     1  ResourceID
+     1  ResourceTable
+     1  Rule
+     2  SCRIPTS
+     1  SETTINGS
+     1  SE_main_arm1_attach
+     1  SE_main_arm1_detach
+     1  SE_main_arm2_attach
+     1  SE_main_arm2_detach
+     1  SE_main_arm3_attach
+     1  SE_main_arm3_detach
+     1  SE_nose_attach
+     1  SE_nose_detach
+     1  SOUND
+     1  SOUNDS
+     1  SQUADRON_ORDER_OBJECT
+     2  STAGE
+     1  STAGES
+     1  SUB_OBJECTIVE
+    11  SYSTEM
+     4  StageResource
+     1  TEXTS
+     2  UNITS
+     1  UnitMessageSetTable
+     2  WEAPONS
+     1  WeaponChangeFrame
+
+## sub_824482D0 -- read an int  (54 distinct)
+     1  ADJUST_X
+     1  ADJUST_Y
+     1  BlinkCycle
+     1  BulletLimit
+     1  ColorEmphasis1
+     1  ColorEmphasis2
+     1  ColorNormal
+     4  Count
+     1  CrewCount
+     1  DOF_Enable
+     1  ENTRY_POINT_PARAM
+     1  EXIT_VALUE
+     2  FINAL_LINE_PITCH
+     1  FinalPassType
+     1  GlareType
+     1  GuidanceType
+     1  HPGauge
+     1  HPGaugeSub
+     1  HP_CLASS
+     1  HP_ID
+     4  LINE_PITCH
+     3  LINE_SPACE
+     2  MISSION_ID
+     2  MSG_FONT_SIZE
+     1  MSG_LINE_PITCH
+     1  MSG_TEXT_LINE
+     1  MegaTons
+     1  NAME_FONT_SIZE
+     1  PLANE
+     1  PREPARE_WAIT
+     1  SPEAKER_HEIGHT
+     1  SUBTITLE_HEIGHT
+     1  SUBTITLE_Y
+     1  SpiralType
+     1  Stage
+     1  Straight1Type
+     1  Straight2Type
+     3  TEXT_HEIGHT
+     2  TEXT_LINE_SPACE
+     1  TEXT_SPEED_PER_LETTER
+     1  VESSEL
+     1  WEAPON_CATEGORIES
+     1  eye_stick_play
+     1  main_arm1_attach
+     1  main_arm1_detach
+     1  main_arm2_attach
+     1  main_arm2_detach
+     1  main_arm3_attach
+     1  main_arm3_detach
+     1  mov_stick_play
+     1  mov_trigger_play
+     1  nose_attach
+     1  nose_detach
+     1  pitch0