docs(node): confirm v6.6 SC migration model, add version-scoping note for operators

[alexander-sei]

Context

A review finding on the SC config docs claimed the [state-commit] model on the skills-registry branch (memiavl_only migration enum + sc-keys-to-migrate-per-block) described "unreleased main". That finding is outdated as of this morning: v6.6.0-rc1 (tagged 2026-07-02) ships exactly this model, so the branch text is correct for v6.6 and stays.

Verified against sei-chain tags v6.5.2, v6.6.0-rc1, and main @ 9f53204:

	v6.5.x (stable)	v6.6.0-rc1	main (post-#3650)
sc-write-mode	cosmos_only / dual_write / split_write	memiavl_only → migrate_evm → … → flatkv_only	same enum + auto
sc-read-mode / sc-enable-lattice-hash	exist	removed	removed
drain rate	n/a	sc-keys-to-migrate-per-block (app.toml, default 1024)	NumKeysToMigratePerBlock gov param (default 0)
mode selection	manual	manual	sc-write-mode-enable-auto = true derives it, ignores explicit key

Changes (on top of the skills-registry branch)

• Version-scoping <Note> in the Giga Storage section: the SC keys documented here are v6.6+; v6.5.x uses the old key set, and each binary line rejects the other's sc-write-mode values at startup (no compat mapping in app/seidb.go — ParseWriteMode panics), so operators must update app.toml when crossing v6.6. The removed sc-read-mode/sc-enable-lattice-hash keys are merely ignored. Also flags the post-v6.6 gov-driven rework already on main.
• Auto-generated app.toml block: mirror the exact v6.6.0-rc1 template comment for sc-keys-to-migrate-per-block (drain-rate tuning guidance) and drop the extra "defaults to memiavl_only" line so the block matches real seid init output.

🤖 Generated with Claude Code

[cursor]

PR Summary

Low Risk
Markdown-only operator documentation with no runtime or config code changes.

Overview
Documentation-only updates to node/node-operators.mdx for SeiDB [state-commit] settings.

The sc-keys-to-migrate-per-block comment in the default app.toml snippet now explains that 1024 is the production default, suggests 256 for test runs that need slower drains to exercise resume/hybrid-read behavior, and states the key is ignored outside migration write modes.

A new <Note> in the Giga Storage section frames the page’s SC keys as the v6.6+ model (memiavl_only / migration enum), contrasts them with v6.5.x (cosmos_only, dual_write, split_write, plus sc-read-mode and sc-enable-lattice-hash), and gives upgrade guidance. It also calls out unreleased main-only behavior: drain rate moving to governance NumKeysToMigratePerBlock, and sc-write-mode-enable-auto overriding explicit sc-write-mode.

^{Reviewed by Cursor Bugbot for commit 913efa6. Bugbot is set up for automated code reviews on this repo. Configure here.}