fix: DM message ordering, consolidate input toolbar, add rich text/WYSIWYG, file upload with drag-drop

- Fix DM backend ListMessages to use DESC + reverse (match channel handler)
- Remove spurious .reverse() from frontend message/conversation stores
- Create shared MessageInput component with Slack-style single toolbar row
- Add file upload via + button with progress bar and drag-and-drop
- Add markdown/rich text toggle with full WYSIWYG block formatting
  (lists, blockquotes, links, headings, code blocks)
- Add frontend+backend security for file uploads (extension + content-type guards)

web/package-lock.json

@@ -8,6 +8,9 @@
       "name": "dumpster-web",
       "version": "0.0.0",
       "dependencies": {
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+        "@fortawesome/free-solid-svg-icons": "^7.3.0",
+        "@fortawesome/react-fontawesome": "^3.3.1",
         "@livekit/components-react": "^2.9.21",
         "@livekit/track-processors": "^0.7.2",
         "emoji-picker-react": "^4.19.1",
@@ -748,6 +751,52 @@
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       "license": "MIT"
     },
+    "node_modules/@fortawesome/fontawesome-common-types": {
+      "version": "7.3.0",
+      "resolved": "https://registry.npmjs.org/@fortawesome/fontawesome-common-types/-/fontawesome-common-types-7.3.0.tgz",
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+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
+    "node_modules/@fortawesome/fontawesome-svg-core": {
+      "version": "7.3.0",
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+      "license": "MIT",
+      "dependencies": {
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+      },
+      "engines": {
+        "node": ">=6"
+      }
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+    "node_modules/@fortawesome/free-solid-svg-icons": {
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+      "license": "(CC-BY-4.0 AND MIT)",
+      "dependencies": {
+        "@fortawesome/fontawesome-common-types": "7.3.0"
+      },
+      "engines": {
+        "node": ">=6"
+      }
+    },
+    "node_modules/@fortawesome/react-fontawesome": {
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+        "react": "^18.0.0 || ^19.0.0"
+      }
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     "node_modules/@jridgewell/gen-mapping": {
       "version": "0.3.13",
       "resolved": "https://registry.npmjs.org/@jridgewell/gen-mapping/-/gen-mapping-0.3.13.tgz",