docs(config): document temp_upload server config + ovcli.conf upload.mode (#1899)

[r266-tech]

Summary

#1899 (feat(server): add shared temp upload mode by @zhoujh01, merged 2026-05-08T03:12Z) introduces two new public config surfaces, but docs/{en,zh}/guides/01-configuration.md (the canonical config reference) was not updated:

1. server.temp_upload (in ov.conf) — new block with default_mode / shared_max_size_bytes / shared_prefix. Source of truth: openviking/server/config.py:98-105 (TempUploadConfig).
2. upload.mode (in ovcli.conf) — new optional client field selecting "local" vs "shared" per request, also overridable via OPENVIKING_UPLOAD_MODE. Source of truth: openviking_cli/utils/config/ovcli_config.py:18 (OVCLIUploadConfig.mode).

#1899 already added these to API docs (docs/{en,zh}/api/{01-overview,02-resources,04-skills}.md etc.), but operators landing on the central config reference would not learn either field exists.

What this PR does

EN + ZH dual-doc mirror, ~10 LOC additive each, single section pair (no relocation, no deletions):

• ovcli.conf example: add "mode": "local" (safe default) to the upload block + add upload.mode row to the field table with both modes explained and the OPENVIKING_UPLOAD_MODE env override called out.
• ov.conf server section example: add the temp_upload block alongside cors_origins + add 3 rows to the field table for temp_upload.default_mode, temp_upload.shared_max_size_bytes, temp_upload.shared_prefix.

Defaults verified against server/config.py ("local" / 536870912 bytes / "viking://upload").

Why this scope

• Stays inside the canonical config reference doc; doesn't touch API or guide docs (feat(server): add shared temp upload mode #1899 already covered those).
• Example uses "mode": "local" (the safe default), so copy-paste does not silently opt single-node users into distributed shared-store behavior.
• Skips the "Full Schema" tail block at the bottom of the page — that block already omits observability, storage.transaction, etc., and looks intentionally trimmed; bringing temp_upload there alone would be inconsistent.

Test plan

• Verify EN + ZH config reference now mention both upload.mode and server.temp_upload.*.
• Confirm defaults ("local", 536870912, "viking://upload") still match openviking/server/config.py TempUploadConfig.

If any wording on the shared-mode caveat ("required when consumer requests can land on a different server instance") undersells or oversells the cross-replica requirement, happy to tighten.

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PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 1899 - Fully compliant Compliant requirements: Documented server.temp_upload in both languages Documented upload.mode in both languages Defaults match source code

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🏅 Score: 100

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ No major issues detected

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