fix: use visually-hidden clip pattern for file inputs

The opacity:0 approach caused the native "Choose File" button to
appear in the accessibility tree and compete for clicks. The clip
pattern properly hides the input while keeping it functional for
programmatic .click().

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/AppsTab/AppsTab.tsx

@@ -303,7 +303,7 @@ function CreateAppView({ environments, selectedEnv }: { environments: Environmen
         <span className={styles.configLabel}>Application JAR</span>
         <div className={styles.fileRow}>
           <input ref={fileInputRef} type="file" accept=".jar"
-            style={{ position: 'absolute', width: 0, height: 0, opacity: 0, overflow: 'hidden' }}
+            style={{ position: 'absolute', width: 1, height: 1, margin: -1, padding: 0, overflow: 'hidden', clip: 'rect(0,0,0,0)', border: 0 }}
             onChange={(e) => setFile(e.target.files?.[0] ?? null)} />
           <Button size="sm" variant="secondary" type="button" onClick={() => fileInputRef.current?.click()} disabled={busy}>
             {file ? 'Change file' : 'Select JAR'}
@@ -541,7 +541,7 @@ function AppDetailView({ appId, environments, selectedEnv }: { appId: string; en
         </div>
         <div className={styles.detailActions}>
           <input ref={fileInputRef} type="file" accept=".jar"
-            style={{ position: 'absolute', width: 0, height: 0, opacity: 0, overflow: 'hidden' }}
+            style={{ position: 'absolute', width: 1, height: 1, margin: -1, padding: 0, overflow: 'hidden', clip: 'rect(0,0,0,0)', border: 0 }}
             onChange={handleUpload} />
           <Button size="sm" variant="primary" type="button" onClick={() => fileInputRef.current?.click()} loading={uploadJar.isPending}>Upload JAR</Button>
           <Button size="sm" variant="danger" onClick={() => setDeleteConfirm(true)}>Delete App</Button>