refactor(chat): remove a needless alias and correct an eslint-disable reason

Self-audit for shortcuts, prompted by 'nothing hacky':

- handlePaste kept `const prepared = preparedSelection`, an alias added only to
  avoid renaming two downstream lines. Uses the real name now.
- The home.tsx drain's eslint-disable claimed handleContextAdd is 'a stable body
  function'. It is a body function, so it is a NEW value every render — the
  justification was false. Replaced with the actual reason: it is omitted to keep
  the drain one-shot, and doing so is harmless because consume() clears
  atomically, so a re-run would find nothing.

Audited the rest of the diff for suppressions, casts and swallowed errors. The
three catch blocks are documented graceful degradations with explicit fallbacks
(row-drain failure, browsers rejecting a custom clipboard MIME mid-gesture,
malformed clipboard JSON); the one double cast is a DataTransfer stub in a test.

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/home/components/user-input/components/prompt-editor/use-prompt-editor.ts

@@ -940,14 +940,13 @@ export function usePromptEditor({
       : null
     if (preparedSelection) {
       e.preventDefault()
-      const prepared = preparedSelection
       const selStart = textarea.selectionStart ?? valueRef.current.length
       const selEnd = textarea.selectionEnd ?? selStart
       const needsSpaceBefore = selStart > 0 && !/\s/.test(valueRef.current.charAt(selStart - 1))
-      const insert = `${needsSpaceBefore ? ' ' : ''}@${prepared.label} `
+      const insert = `${needsSpaceBefore ? ' ' : ''}@${preparedSelection.label} `
       textarea.setRangeText(insert, selStart, selEnd, 'end')
       const caret = selStart + insert.length
-      contextManagementRef.current.addContext(prepared)
+      contextManagementRef.current.addContext(preparedSelection)
       valueRef.current = textarea.value
       setValueState(textarea.value)
       requestAnimationFrame(() => textarea.setSelectionRange(caret, caret))

apps/sim/app/workspace/[workspaceId]/home/home.tsx

@@ -358,7 +358,11 @@ export function Home({ chatId, userName, userId, tableViewsEnabled }: HomeProps)
     const contexts = handoff.contexts ?? []
     for (const context of contexts) handleContextAdd(context)
     addMothershipContexts(contexts)
-    // eslint-disable-next-line react-hooks/exhaustive-deps -- one-shot drain; handleContextAdd is a stable body function
+    // `handleContextAdd` is a body function, so it is a new value every render;
+    // listing it would re-run this drain on every render. Omitted deliberately to
+    // keep it one-shot — and harmless either way, since `consume` clears the entry
+    // atomically and any re-run would find nothing.
+    // eslint-disable-next-line react-hooks/exhaustive-deps -- see above
   }, [chatId, workspaceId, sendMessage])
 
   function resolveResourceFromContext(