Docs: Finalized v0.25.6 release notes. (#15305)

### What problem does this PR solve?

Finalized v0.25.6 release notes.

### Type of change

- [x] Documentation Update

docs/release_notes.md

@@ -19,27 +19,30 @@ Released on May 26, 2026.
 
 ### Improvements
 
-- RAG: RAPTOR construction now introduces AHC mode (Ψ-RAG), which expands semantics from the document level to the dataset level. Not only is index construction performance significantly higher than the previous RAPTOR, but it also outperforms the old RAPTOR on Recall@5 and average F1. Users can switch between AHC and GMM modes. This feature was introduced in v0.25.3, and this release fixes several bugs. [#14674](https://github.com/infiniflow/ragflow/issues/14674)[#14679](https://github.com/infiniflow/ragflow/pull/14679)
+- RAG: Stabilizes RAPTOR's AHC mode (Ψ-RAG), which was introduced in v0.25.3 to resolve previous semantic loss by building individual document trees and then merging them hierarchically. This new approach significantly accelerates index construction and outperforms the legacy GMM mode in Recall@5 and average F1. Users retain the option to switch between the two modes. [#14674](https://github.com/infiniflow/ragflow/issues/14674)[#14679](https://github.com/infiniflow/ragflow/pull/14679)
 - Agent: Introduces lightweight `@tool` decorator to streamline Python function registration process for chat models. [#15047](https://github.com/infiniflow/ragflow/pull/15047)
 - Agent: Enables agent messages to display base64-encoded images. [#15212](https://github.com/infiniflow/ragflow/pull/15212)
 - Agent: Exposes **Doc Generator** component's file metadata as discrete variables. [#15080](https://github.com/infiniflow/ragflow/pull/15080)
-- Agent: Allows developers to pass `chat_template_kwargs` to agent chat completion endpoint. [#14182](https://github.com/infiniflow/ragflow/issues/14182)[#14542](https://github.com/infiniflow/ragflow/pull/14542)
+- Agent: Allows developers to pass `chat_template_kwargs` to agent chat completion endpoint. [#14182](https://github.com/infiniflow/ragflow/issues/14182)[#14542](https://github.com/infiniflow/ragflow/pull/14542) See also [Converse with agent](./references/http_api_reference.md#converse-with-agent)
 
 ### Bug fixes
 
 - Fixes `/chat/completions` to allow sending only latest message in API payload and removes requirement to transmit full conversation history. [#15197](https://github.com/infiniflow/ragflow/pull/15197) See also [Converse with chat assistant](./references/http_api_reference.md#converse-with-chat-assistant).
-- Weight assigned to vector similarity was not applied during the retrieval phase. [#15108](https://github.com/infiniflow/ragflow/pull/15108)
-- Fixes parser configs not saving on dataset configuration page.
-- Logs were not fully displayed on data source details page.
-- Fixes document status filtering failure.
-- Fixes crash guard for empty LLM choices responses.
+- Weight assigned to vector similarity was not properly applied during the retrieval phase. [#15108](https://github.com/infiniflow/ragflow/pull/15108)
+- Users were unable to save parser configurations on the dataset configuration page. [#15175](https://github.com/infiniflow/ragflow/issues/15175)[#15177](https://github.com/infiniflow/ragflow/pull/15177)
+- Log text on a data source's details page was truncated. [#15056](https://github.com/infiniflow/ragflow/pull/15056)
+- An unresponsive "Status" filter on the document list page prevented users from filtering or managing uploaded documents by their parsing status. [#15170](https://github.com/infiniflow/ragflow/issues/15170)[#15216](https://github.com/infiniflow/ragflow/pull/15216)
+- Calling `GET /agents/<agent_id>/sessions/<session_id>` with a missing or invalid session ID caused a server error. [#14989](https://github.com/infiniflow/ragflow/issues/14989)[#15011](https://github.com/infiniflow/ragflow/pull/15011)
 - RAG: RAPTOR construction process halted when using the [Infinity](https://github.com/infiniflow/infinity) document engine. [#14998](https://github.com/infiniflow/ragflow/pull/14998)
-- Fixes streaming response parsing for Mistral/Upstage reasoning models.
-- Fixes HTML tags in ingestion pipeline parser output.
-- Fixes table parser metadata.
-- Fixes asyncio event loop nesting and fire-and-forget task issues.
-- Fixes asyncio.Semaphore bound to different event loop error.
-- Agent: Fixes **Agent** component prompt variable disappearing and search vector_similarity_weight issues.
+- The system failed to correctly parse structured content returned by Mistral reasoning models. [#14805](https://github.com/infiniflow/ragflow/pull/14805)
+- The **Parser** component in an ingestion pipeline incorrectly retained raw HTML tags in its text output. [#14831](https://github.com/infiniflow/ragflow/issues/14831)[#14920](https://github.com/infiniflow/ragflow/pull/14920)
+- The table parser incorrectly extracted or attached metadata during document processing. [#15127](https://github.com/infiniflow/ragflow/pull/15127)
+- Asynchronous background tasks and nested event loops were not properly handled, causing backend instability. [#14755](https://github.com/infiniflow/ragflow/issues/14755)[#14761](https://github.com/infiniflow/ragflow/pull/14761)
+- Prompt variables configured in the **Agent** component disappeared after being entered. [#15218](https://github.com/infiniflow/ragflow/pull/15218)
+
+### i18n
+
+- Fully translates the interface into French with the addition of roughly 1,400 localization keys. [#15192](https://github.com/infiniflow/ragflow/pull/15192)
 
 ## v0.25.5