refactor: rename prompts.ts to prompt.ts and update imports

Author: splinesreticulating

src/lib/khoj.ts

@@ -1,5 +1,5 @@
 import { KHOJ_AGENT, KHOJ_API_URL } from '$env/static/private'
-import { PERMANENT_CONTEXT, buildKhojPrompt } from '$lib/prompts'
+import { PERMANENT_CONTEXT, buildKhojPrompt } from '$lib/prompt'
 import type { Message, ToneType } from '$lib/types'
 import { extractReplies, formatAsUserAndAssistant, parseSummaryToHumanReadable } from '$lib/utils'
 import { fetchRelevantHistory } from './history'

src/lib/openAi.ts

@@ -8,7 +8,7 @@ import {
 } from '$env/static/private'
 import { fetchRelevantHistory } from './history'
 import { logger } from './logger'
-import { PERMANENT_CONTEXT, buildReplyPrompt } from './prompts'
+import { PERMANENT_CONTEXT, buildReplyPrompt } from './prompt'
 import type { Message, OpenAIConfig, ToneType } from './types'
 import { formatAsUserAndAssistant } from './utils'