docs: proactively fix the vi.fn spread-args TS2556 pattern in remaining tasks

Task 3's implementer independently hit and fixed this exact bug
(a vi.fn() given a zero-arg implementation, then invoked via a spread
of unknown[] args inside a vi.mock factory, fails tsc -b with TS2556).
Applied the same fix (explicit vi.fn<...> generic type) to the other
occurrences of this pattern still written the old way in this plan's
Task 3 and Task 4 sections, so those implementers don't have to
rediscover it from scratch. Task 5, 10, and 11's occurrences were
checked and found to already use safe patterns (single literal-arg
calls, or bare vi.fn() with no implementation) that don't trigger this.

Claude-Session: https://claude.ai/code/session_01NhxA4npAXAxmCDEJt6kxSH

docs/superpowers/plans/2026-08-12-phase2c-public-site-live-data.md

@@ -367,7 +367,7 @@ import { describe, it, expect, vi, beforeEach } from 'vitest'
 
 const orderMock = vi.fn()
 const selectMock = vi.fn(() => ({ order: orderMock }))
-const fromMock = vi.fn(() => ({ select: selectMock }))
+const fromMock = vi.fn<(...args: unknown[]) => { select: typeof selectMock }>(() => ({ select: selectMock }))
 const resolveImageUrlMock = vi.fn((path: string) => `https://cdn.example/${path}`)
 
 vi.mock('../lib/supabase', () => ({
@@ -537,7 +537,7 @@ import { describe, it, expect, vi, beforeEach } from 'vitest'
 
 const orderMock = vi.fn()
 const selectMock = vi.fn(() => ({ order: orderMock }))
-const fromMock = vi.fn(() => ({ select: selectMock }))
+const fromMock = vi.fn<(...args: unknown[]) => { select: typeof selectMock }>(() => ({ select: selectMock }))
 const resolveImageUrlMock = vi.fn((path: string) => `https://cdn.example/${path}`)
 
 vi.mock('../lib/supabase', () => ({