Undo build button grid icons

Remove the per-building SVG icons and all their wiring (the icon assets,
the QtSvg-based icon loading in BuildButtonGrid, the icon dir plumbing in
MainWindow, and the Qt5::Svg dependency), leaving only the Demolish ->
Deconstruct rename from the previous commit.

This is the inverse of the icon half of the previous commit, paired with a
following revert that re-adds the icons. Cherry-picking the previous
"rename + icons" commit together with this undo reconstructs the rename on
its own.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y7N59FsLA5e2kuVdqe4Uhc

bin/app/data/icons/buildings/assembler.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#3a6fa8"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <circle cx="16" cy="16" r="6.2"/><circle cx="16" cy="16" r="2.2"/><path d="M16 5.5v3M16 23.5v3M5.5 16h3M23.5 16h3M8.6 8.6 10.7 10.7M23.4 8.6 21.3 10.7M8.6 23.4 10.7 21.3M23.4 23.4 21.3 21.3"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/belt.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#6a6a6a"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <rect x="4" y="10" width="24" height="12" rx="3"/><path d="M9 13 12.5 16 9 19"/><path d="M14.5 13 18 16 14.5 19"/><path d="M20 13 23.5 16 20 19"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/deconstruct.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#cc3333"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M7 10h18"/><path d="M9.5 10 11 26h10l1.5-16"/><path d="M13 10V6.5h6V10"/><path d="M13.5 14v8M18.5 14v8"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/miner.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#6b4a2c"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <rect x="9" y="5" width="14" height="8" rx="1.5"/><path d="M11 13 16 26 21 13"/><path d="M13 17.5h6"/><path d="M14.5 21.5h3"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/reprocessing_plant.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#6a3a8a"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <circle cx="12" cy="18" r="4"/><circle cx="20" cy="18" r="4"/><path d="M10.6 16.6 13.4 19.4M13.4 16.6 10.6 19.4M18.6 16.6 21.4 19.4M21.4 16.6 18.6 19.4"/><path d="M16 4v8"/><path d="M13 9 16 12 19 9"/><path d="M16 24v4"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/salvage_bay.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#b8a23a"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M7 13h18l-2 13H9z"/><path d="M16 3v7"/><path d="M12 7 16 11 20 7"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/shipyard.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#3f6580"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M16 4c2 3 2.6 6 2.6 9.5V16h-5.2v-2.5C13.4 10 14 7 16 4z"/><circle cx="16" cy="10" r="1.3"/><path d="M13.4 15 11 18h2.4z"/><path d="M18.6 15 21 18h-2.4z"/><path d="M14.7 17 16 21 17.3 17"/><path d="M9 25h14"/><path d="M12 25v-2M20 25v-2"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/smelter.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#b85a1e"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M9 9h14l-2.5 8h-9z"/><path d="M8 9h16"/><path d="M11 26c-1-1.8.4-3 .4-4 .9 1 1.6 2.2 1.6 4"/><path d="M16 26c-1-2 .4-3.4.4-4.4 .9 1 1.6 2.6 1.6 4.4"/><path d="M21 26c-1-1.8.4-3 .4-4 .9 1 1.6 2.2 1.6 4"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/splitter.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#7a7a5a"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M5 16h11"/><path d="M16 8v16"/><path d="M13.5 10.5 16 8 18.5 10.5"/><path d="M13.5 21.5 16 24 18.5 21.5"/>
-  </g>
-</svg>

bin/app/data/icons/buildings/tunnel_entry.svg

@@ -1,6 +0,0 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="100" height="100">
-  <rect width="100" height="100" rx="22" fill="#4f7562"/>
-  <g transform="translate(13,13) scale(2.3125)" fill="none" stroke="#ffffff" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
-    <path d="M4 9h24"/><path d="M8 9C8 24 24 24 24 9"/><path d="M14.5 18.5 17.5 20 14.5 21.5"/>
-  </g>
-</svg>