docs(blog): ground three OpenViking articles in current behavior

[ZaynJarvis]

Why

• Three posts mix outdated behavior, unsupported claims, and repeated abstractions.
• Rewrite plugin setup, context architecture, and adoption guidance; align Chinese, English, and llm.txt.
• Target the blog branch; preserve upstream navigation, 404 pages, and the TOS installer option.
• Record selection rationale, source references, and verification limits.

Tested

• npm --prefix blog run build — 15 static routes and the 404 checks pass.
• npm --prefix blog test — 33 tests pass.
• git diff --check
• Ego-browser: all three articles in both languages; no page overflow or broken covers. Mobile plugin article has no page overflow.
• Six shell examples pass bash -n; article hashes match the editorial record.
• Not run: plugin installation, backend ingestion, memory extraction, or benchmarks.