fix: crash bugs in TeamInvoices + faster load

Bug fixes:
- TeamInvoices: add useAuth import/currentUser (invoice-create crash)
- TeamInvoices: setChartYear -> setExportYear (year-dropdown crash)
- TeamDashboard: drop redundant setState-in-effect (cascading renders)
- Companies: delete dead _UnusedClientCompanies (illegal hook calls)
- annotate intentional empty PDF-fallback catches

Load speed:
- preconnect/dns-prefetch to Supabase origin
- lazy-load heic-to in Converters: page chunk 2737KB -> 9KB
- split recharts into its own 'charts' vendor chunk

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/FileAttachment.jsx

@@ -1,4 +1,4 @@
-import { useState, useRef } from 'react';
+import { useId, useRef, useState } from 'react';
 
 const MAX_FILES = 20;
 const MAX_SIZE_MB = 250;
@@ -10,6 +10,7 @@ const formatSize = (bytes) => {
 };
 
 export default function FileAttachment({ files, onChange }) {
+  const inputId = useId();
   const [errors, setErrors] = useState([]);
   const [dragging, setDragging] = useState(false);
   const dragCounter = useRef(0);
@@ -79,8 +80,8 @@ export default function FileAttachment({ files, onChange }) {
           transition: 'all 160ms', cursor: 'pointer',
         }}
       >
-        <input type="file" multiple onChange={handleChange} style={{ display: 'none' }} id="req-file-upload" />
-        <label htmlFor="req-file-upload" style={{ cursor: 'pointer', textTransform: 'none', letterSpacing: 'normal', fontWeight: 400 }}>
+        <input type="file" multiple onChange={handleChange} style={{ display: 'none' }} id={inputId} />
+        <label htmlFor={inputId} style={{ cursor: 'pointer', textTransform: 'none', letterSpacing: 'normal', fontWeight: 400 }}>
           <div style={{ fontSize: 20, marginBottom: 4 }}>{dragging ? '📂' : '📎'}</div>
           <div style={{ fontSize: 13, color: 'var(--text-primary)' }}>
             {dragging