fix(config): a missing seed YAML must not start setup over live Settings

[frahlg]

A missing leftover config.yaml starts the setup wizard even when state.db already holds Settings. Finishing the wizard can commit that new YAML over live configuration.

Found on master 6eadec3f (schema 2: settings live in SQLite; YAML is a locator and rollback seed).

What happens

cfg, err := config.Load(*configPath)
if err != nil {
    if isConfigMissing(*configPath) {
        runBootstrap(*configPath, *webDir, resolveDriverDir())
        return
    }
}

isConfigMissing is only Lstat of the seed path. It does not look for state.db or settings/config_v1.

The wizard writes a new YAML. InitializeStorage then sees an existing settings row whose YAMLSourceHash does not match the new file, sets legacySave, and saveStored commits the wizard document over the live Settings (go/internal/config/storage.go).

The same legacySave path fires if the leftover seed is edited or config_database is removed: YAML becomes authority again.

TestMissingDatabaseDoesNotStartSetup only covers the inverse (locator present, DB gone).

What a fix needs

• If state.db already has settings/config_v1, do not enter the wizard because the seed file is missing. Recreate the locator YAML from SQLite instead.
• Refuse legacySave when the new YAML is a wizard/default document rather than an old-Core rollback save.
• Tests: delete config.yaml, keep state.db with Settings, start Core — Settings unchanged, locator rewritten, wizard not shown.
• Same for an edited leftover seed.

This is a data-loss path on every schema-2 box that still has a seed file beside the DB (the documented layout).