Synapse v1.7.1 — "post-1.7.0 fixes: output language, knowledge graph, onboarding UX"

Patch release fixing issues surfaced right after 1.7.0.

Fixed

• The knowledge graph collapsed on multi-vault deployments. Wikilink resolution built its slug→page map over all vaults' pages (no vault_id filter), so when vaults share page slugs a link resolved cross-vault and produced no graph edge. Measured on an 8-vault DB: 50 graph-eligible links became 5 edges. _build_resolver_maps and the graph engine's link query are now vault-scoped. Single-vault deployments were unaffected.
• overview.md ignored the per-vault output language. Regeneration resolved language from content detection, so an Italian vault built from English sources got an English overview. It now honors vault_state.output_language.
• The first-run setup wizard reappeared on every reload. Skipping it (defer) only hid it for the current session. Both "completed" and "deferred" now suppress the auto-show across sessions.

Added

• Settings → Appearance → "AI Output Language". Change a vault's generation language after creation (previously only settable in the new-project wizard); saves immediately via PUT /vault/meta/output-language.
• D5 Home dashboard screenshot + its Playwright capture spec.

Upgrade

No Alembic migrations. The graph fix takes effect for new ingests. To reconnect an existing multi-vault graph, re-ingest the affected vault (links re-resolve to the right pages). Pull new images.