bug(api): completion-conversations end-time filter uses strict `<` instead of `<=`, silently dropping boundary conversations

从 api/controllers/console/app/conversation.py 中的 CompletionConversationApi.get 开始，然后将其结束时间处理方式与 Chat conversation endpoint 进行比较。验证在所选分钟的最后一秒创建的 conversation 会被 completion-conversations 过滤器包含，符合文档中描述的预期行为。

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Dify version

1.17.0 (main branch, commit 6bc7f01261)

Cloud or Self Hosted

Self Hosted (Docker)

Steps to reproduce

1. In the Dify console, open any Completion-type app's conversation log page.
2. Set a date/time filter with an end time, e.g. 2024-01-15 14:30.
3. Note which conversations are returned.
4. Compare results with a Chat-type app using the same end-time filter.

✔️ Expected Behavior

Both Completion and Chat conversation list endpoints should use an inclusive upper bound (<=) for the end-time filter. A conversation created at exactly 2024-01-15 14:30:59 (the last second of the specified end minute) should appear in the results.

❌ Actual Behavior

The Completion conversation endpoint (GET /apps/<id>/completion-conversations) uses a strict less-than (<) comparison for the end-time, which silently excludes conversations created at exactly the boundary second.
The Chat conversation endpoint (GET /apps/<id>/chat-conversations) correctly uses <=.

Root Cause (Code Evidence)

Both endpoints call parse_time_range() which parses end time as HH:MM with second=0, then both immediately call .replace(second=59) — clearly intending to include the full minute up to :59. But the comparison operators then diverge:
CompletionConversationApi.get — api/controllers/console/app/conversation.py line 141-143 (BUG):

if end_datetime_utc:
    end_datetime_utc = end_datetime_utc.replace(second=59)
    query = query.where(Conversation.created_at < end_datetime_utc)  # ← strict <