Pre-Alpha 0.1.7 — Icon, graphic & button improvements

Pre-Alpha 0.1.7 for iPad and iPhone. Unsigned IPA — sideload with AltStore, SideStore or
Xcode. You still need your own Daggerfall arena2 folder; see README-iOS.md for setup.

This release is about how the touch HUD looks, plus three buttons that were missing.

Every custom icon redrawn

All 21 illustrated icons were regenerated and replaced. The old set never quite looked like
Daggerfall, and measuring it against the game's own ART_PAL.COL showed why: 39.7% of its
pixels sat above value 200 — a specular blowout that 1996 VGA item art simply doesn't have.
The art was being asked for it directly, with terms like "thick dark outline", "high contrast"
and "bright highlights". Those are modern game-icon conventions. The new set describes the
digitized painted look of the real thing instead.

Every icon is then conditioned to the house style measured off the shipped art — a 56×56
native grid, hard pixel edges with no anti-aliasing, and quantisation to a sampled
palette. Each one now lands at 24–58 colours, against a house range of 51–82.

The two 4-colour placeholders, btn_menu and btn_pause, are real art at last.

Joysticks are drawn, not generated

The ring and knob are geometry rather than illustration — the knob has to read as concentric
with the ring no matter where you drag it. Image generation can't deliver that: the generated
ring measured aspect 1.041, visibly tilted, and the knob was too big to sit inside it.

Both are now computed analytically on the same 56×56 grid — true circles, knob radius 16
against ring inner radius 18.5, giving 2.5 px of clearance. This also retires the old knob,
which was the single worst-matching asset in the set at 852 colours.

Three missing buttons

• Character sheet — opens your character record, in both classic and non-classic modes.
• Interaction mode — cycles Grab → Info → Talk → Steal. Steal is how you pick a lock on
  touch: cycle to it, then tap the door with the action button.
• Automap — non-classic fullscreen had no way to open the dungeon map. It does now.
  (The travel map is unchanged; it already worked.)

Tapping a locked door you can't open now shows a proper Daggerfall-styled message instead of
doing nothing.

Known rough edges

Five icons are weaker than the rest and are already queued for another pass:
btn_combat_off reads faint, btn_back looks more like a crescent than an arrow,
btn_crouch goes murky at small size, btn_jump reads as a bird rather than a boot, and
rest / map / sheet are three rolled-parchment shapes that can be confused in a row.

Mods remain loose-file only — .dfmod code mods can't run on iOS, since IL2CPP has no
runtime compiler. See README-iOS.md.