[doc](4.1.4) Update Chinese 4.x docs for the 4.1.4 release

[morningman]

What this PR does

Reviewed every commit between 4.1.3 and 4.1.4-rc04 (431 commits, 340 of which touch production code) and brought the Chinese 4.x documentation in line with the release.

Chinese only for now, on purpose — the English pages and dev will be synced after this is reviewed.

Corrections to statements that were already wrong

Doc said	Reality
require_partition_filter supported since 4.1.2	Not in 4.1.2 or 4.1.3; lands in 4.1.4
Multimodal EMBED supported since 4.1.5	Lands in 4.1.4
Paimon catalog depends on Paimon 1.0.0	4.1.3 shipped 1.3.1, 4.1.4 ships 1.4.2
Several "since 4.0.8" notes	Only reached the 4.1 line in 4.1.4 — fe_meta_auth_token, autobucket_min_buckets, group commit BE forwarding, Stream Load compute group, Routine Load FirstErrorMsg, enable_file_cache_write_index_file_only
iceberg_meta() TVF documented as available	Removed in 4.1.4
position_deletes system table "not supported yet"	Supported since 4.1.4
ANN index "only on Duplicate Key tables"	Also allowed on merge-on-write Unique Key tables

New / changed user-facing surface now documented

SQL and interfaces

• ADMIN COMPACT TABLET <id> WHERE TYPE=...
• Removal of iceberg_meta(), the /api/.../upload endpoints and http_load_submitter_max_worker_threads
• SHOW CLUSTERS / SHOW COMPUTE GROUPS now work in non-cloud mode, with different columns and relaxed privileges
• New pages for parse_to_variant() / try_parse_to_variant()

Lakehouse

• Iceberg: VARIANT read/write, V3 initial-default / write-default and the DEFAULT() expression, nested-column DDL, ALTER TABLE ... SET, database property matrix, $position_deletes, Alibaba OSS Tables REST catalog, mixed Parquet/ORC data files, MERGE INTO duplicate-match check
• Hive: __HIVE_DEFAULT_PARTITION__ now reads as a real NULL
• MaxCompute: test_connection, and the timeout/retry properties now taking effect
• File Scanner V2, BE-side split refinement (file_split_size_on_fe / file_split_size_on_be) and external scan task reuse

Load

• Streaming jobs: OceanBase source, MySQL ADD/DROP COLUMN sync and schema_change_enabled, Lag → LagBytes, JDBC URL normalization (TINYINT(1) and YEAR mapping changes), snapshot_split_size default 8096 → 40960
• Group commit: group_commit_max_wal_num_per_table, follower forwarding
• Stream Load: table-scoped LOAD_PRIV is now sufficient

Other

• FLOAT/DOUBLE to string now uses the shortest round-trip form
• New FE and BE configuration entries
• A new "upgrading to 4.1.4" section in the upgrade guide covering removals, default changes and deployment changes (including the JDK 17 --add-opens=java.base/java.nio=org.apache.arrow.memory.core,ALL-UNNAMED change)
• A session-variable reference page, covering only the variables 4.1.4 touches, explicitly marked as work in progress

Deliberately left out

• Paimon write support (INSERT / INSERT OVERWRITE / row-level UPDATE / DELETE / MERGE INTO, the associated DDL and paimon_jni_writer_memory_pool_limit_bytes) — not an officially released capability yet. The Paimon 1.4.2 dependency bump is kept.
• Variant V2 — the FE config enable_variant_v2, the ColumnVariantV2 section on the VARIANT type page, and the Iceberg / Paimon VARIANT column support gated on it. parse_to_variant() / try_parse_to_variant() are kept: they are registered unconditionally and their BE implementation builds a legacy ColumnVariant, so they do not depend on enable_variant_v2.
• The unified TLS framework — the open-source build only ships the framework and no-op implementations.

English and dev are now synced

The third commit ports everything to versioned_docs/version-4.x/ (English 4.x), docs/ (English dev) and i18n/zh-CN/.../current/ (Chinese dev), and wires the new pages into versioned_sidebars/version-4.x-sidebars.json and sidebars.ts.

The dev trees are not a copy — master has diverged from branch-4.1, and every factual claim was re-checked against it:

Item	4.1.4	master	Dev docs say
enable_external_scan_task_reuse, file_split_size_on_fe, file_split_size_on_be, external_meta_cache_max_weight	exist	absent	omitted
enable_expr_zonemap_filter	false	true	true
meta_service_rpc_rate_limit_enabled	false	true	true
max_scanners_concurrency	8	4	unchanged, note dropped
paimon.version	1.4.2	1.3.1	1.3.1
paimon-scanner → paimon-connector	renamed	not renamed	note dropped
Iceberg database properties beyond HMS, ALTER TABLE ... SET on Iceberg	supported	not supported	sections skipped
SHOW TABLETS with LIMIT and no ORDER BY	sorted prefix	scan order	reworded

Several Iceberg error strings also differ on master (Cannot specify invisible column ..., DEFAULT requires a target column reference); the dev text follows master.

Corrections found while porting

Reviewing each claim against the source turned up mistakes in the Chinese pages, now fixed in all four trees:

• default.replication_num / default.replication_allocation are not mutually exclusive — modifying one removes the conflicting legacy property, with a rolling-upgrade caveat.
• The enable_nereids_distribute_planner refresh is gated on variable_version < 400, so it only applies to a 3.x → 4.1.4 upgrade, not to every upgrade.
• enable_forward_group_commit_stream_load_to_follower is mutable and default_get_version_from_ms_timeout_second is not — both were stated the wrong way round.
• SHOW COMPUTE GROUPS.BackendNum counts every backend in the group, not only the live ones (getAllClusterBackends(false)).
• The floating-point example (cast('12345678' as float) → 1.234568e+07) contradicted the new shortest-round-trip rule it sat under.
• The MaxCompute test_connection row had been inserted mid-table, splitting it in two, and named the property mc.enable_namespace_schema instead of mc.enable.namespace.schema.

Also in this PR

• schema-change-mysql.md ported from dev down to 4.x — MySQL schema change sync ships in 4.1.4 and the 4.x overview already points at it.
• parse_to_variant / try_parse_to_variant reuse the existing dev pages instead of the ones written for 4.x, with their version line corrected from 4.2 to 4.1.4 everywhere.

Known gap

require_partition_filter is not documented in the dev trees at all — it was added to dev, removed from dev, then re-added to 4.x only. The property does exist on master, so dev has a real hole, but filling it means writing the feature up rather than porting this change.

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