feat: add verified backup, restore, and logical data transfer

[mahoshojoHCG]

Summary

• add sdw-backup create/list/verify/restore with PostgreSQL custom dumps, config/password/Data Protection/plugin state, compression, retention, optional age encryption, whole-archive and per-file SHA-256 verification, compatibility/space/path preflight, safety snapshots, and failure webhooks
• package the CLI and opt-in systemd timer, wire container backup storage, and document RPO/RTO, media exclusions, upgrade snapshots, encryption, and disaster recovery
• add checksummed, category-selective logical JSON export/import for feeds, automation policies, filename rules, current metadata corrections, playback progress, and preferences with skip/overwrite/fail conflict behavior
• add PostgreSQL round-trip/rollback tests and a CI drill that creates, verifies, rejects corrupted/incompatible restores before writes, restores into a fresh database, and health-checks the recovered app

Media files and transient Valkey state remain intentionally outside the database backup; the recovery guide describes their separate protection requirements. Local directories are the built-in MVP target and the guide defines the boundary for immutable remote uploaders.

Validation

• dotnet test SecondDimensionWatcherReDive.slnx --no-restore — 416 passed
• PostgreSQL logical transfer round-trip, stable-key mapping, idempotency, and transactional rollback — 3 passed
• deployments/tests/backup-restore-smoke.sh — create, verify, corruption rejection, fresh-database restore, and state comparison passed
• dotnet ef migrations has-pending-model-changes ... — no pending model changes
• Bash syntax, workflow YAML parsing, and git diff --check passed

A local Containerfile build reached yarn install --immutable but the registry repeatedly aborted package downloads; the repository's container workflow will retry the complete image build in CI.

Closes #13

[chatgpt-codex-connector]

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-29T14:51:22.736397Z	ef2780e	PR opened

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[chatgpt-codex-connector]

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Reviewed commit: ef2780e2be

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