fix: preserve main schema guard during promotion

[Obed0101]

Purpose

The dev branch did not contain the two recorded-schema guard files that still exist on main. Restoring them before dev-to-main promotion prevents the promotion from deleting existing main paths.

Change

• Restore src/mendcode/packages/opencode/src/storage/recorded-schema.ts.
• Restore its focused installation regression test.

Verification

• Added only the two paths that are present on origin/main and absent from origin/dev.
• No existing dev files were removed.

This PR is a promotion safety prerequisite for beta16.

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