Synapse v1.7.4 — "log/index parity fixes"

Patch release fixing two correctness defects in wiki/log.md and index.md management.

Fixed

• wiki/log.md was corrupted by the block-ingest path. Three issues compounded: the model's log.md block was not dropped (only index.md/overview.md were), so it overwrote the code-managed log and destroyed its frontmatter; schema.md described a second, conflicting "Log Format" the model then emitted; and append_log fired once per generated page (plus bogus entries). Now log.md is app-managed (its block is dropped), schema.md marks it auto-maintained, and the block path appends exactly one ## [YYYY-MM-DD] ingest | <source title> entry per source (llm_wiki parity).
• index.md counted and listed every vault's pages, not the active vault's. update_index ran its page query without a vault_id filter. The query is now vault-scoped.

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