refactor(storage): extract parseJsonColumn helper in organization-settings

[pedrofrxncx]

Source: C1 code-reduction, found while auditing the org-settings storage layer (apps/api/src/storage/organization-settings.ts) for the org-settings-persistence focus area. No related open PR touches this file — #6487/#6481/#6464/#6445 (recently merged/open) all touch update.ts/delete.ts/member-list.ts, not this file.

What/why: OrganizationSettingsStorage.get() inlined the same 'jsonb column may come back as a string or as an already-parsed value' ternary 7 times, once per settings field (sidebar_items, enabled_plugins, registry_config, simple_mode, default_home_agents, flags, sprint_config). Collapsed into one parseJsonColumn<T>() helper called per field. A maintainer gets one place to fix this normalization logic instead of seven.

Net delta: -35 / +28 lines in one file, no behavior change: same null-check, same typeof === "string" ? JSON.parse(...) : value logic, just factored out. Each call site passes an explicit type argument because Kysely's ColumnType select type doesn't infer cleanly through a bare generic parameter (confirmed via tsc --noEmit — inferring from the parameter directly produced a T[][] mismatch).

How a reviewer confirms: read the diff — parseJsonColumn is a straight extraction of the pre-existing ternary, and every field still round-trips through it. No integration test exists for this file that doesn't need real Postgres (this box has none available), so verification here is static: the change is a pure refactor with no schema/query changes.

Checks run locally: bun run fmt, cd apps/api && bunx tsc --noEmit (green), bunx oxlint apps/api/src/storage/organization-settings.ts (0 warnings/errors). Full CI (including the Postgres-backed integration test for this file) validates the rest.

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Summary by cubic

Deduplicates JSON parsing for organization settings by extracting a parseJsonColumn<T>() helper. Behavior is unchanged: the previous per-field ternary becomes a single helper that normalizes string-or-object jsonb values with the same null check.

• No schema or query changes; only get() in apps/api/src/storage/organization-settings.ts is touched.
• Each call site passes an explicit generic due to kysely select type inference limits.
• To review: compare the helper to the prior ternary and confirm all JSON fields (sidebar_items, enabled_plugins, registry_config, simple_mode, default_home_agents, flags, sprint_config) route through it.

^{Written for commit 1bec1b4. Summary will update on new commits.}