refactor(obsidian): move TNMSO to standalone submodule

[TrueNine]

Summary

• replace the inline Obsidian plugin with the TrueNine/tnmso submodule pinned to 2026.10805.0
• require TNMSO to be released before advancing the shared memory-sync version
• initialize the submodule only in version/plugin CI and release jobs
• stop creating duplicate plain-version Obsidian releases from memory-sync

Verification

• version sync tests: 5 passed
• TNMSO tests: 17 passed
• TNMSO typecheck, lint, build, package, and dist verification passed
• version surfaces validated for 2026.10805.0
• actionlint passed

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