store: wire up redb updates on mutations

Mutations (upsert_node, upsert_provenance, delete_node, rename_node)
now update redb indices atomically with capnp log appends, under the
same StoreLock.

Also removes dead cmd_import command and the parse.rs module it depended on.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/main.rs

@@ -318,11 +318,6 @@ enum AdminCmd {
     /// Brief metrics check (for cron/notifications)
     #[command(name = "daily-check")]
     DailyCheck,
-    /// Import markdown file(s) into the store
-    Import {
-        /// File paths
-        files: Vec<String>,
-    },
     /// Output session-start context from the store
     #[command(name = "load-context")]
     LoadContext {
@@ -452,7 +447,6 @@ impl Run for AdminCmd {
             Self::Fsck          => cli::admin::cmd_fsck().await,
             Self::Dedup { apply } => cli::admin::cmd_dedup(apply).await,
             Self::DailyCheck    => cli::admin::cmd_daily_check().await,
-            Self::Import { files } => cli::admin::cmd_import(&files).await,
             Self::LoadContext { stats } => cli::node::cmd_load_context(stats).await,
         }
     }