store: remove dead code and move params to config

Remove:
- score_weight() - never called
- position field on Node - never read (was for export)
- Provenance enum - inline helper for capnp migration
- migrate_transcript_progress + CLI command
- init_from_markdown, import_file, ingest_units
- export command and export_to_markdown
- RetrievalEvent, GapRecord types
- classify_filename, new_transcript_segment

Move spreading activation params to Config:
- default_node_weight, edge_decay, max_hops, min_activation
- Remove Params struct and StoreView::params()

Simplify cmd_init to just seed identity via upsert().
Simplify cmd_import to use parse_units + upsert directly.

-576 lines

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

src/main.rs

@@ -323,14 +323,6 @@ enum AdminCmd {
         /// File paths
         files: Vec<String>,
     },
-    /// Export store nodes to markdown file(s)
-    Export {
-        /// File keys to export (or --all)
-        files: Vec<String>,
-        /// Export all file-level nodes
-        #[arg(long)]
-        all: bool,
-    },
     /// Output session-start context from the store
     #[command(name = "load-context")]
     LoadContext {
@@ -338,9 +330,6 @@ enum AdminCmd {
         #[arg(long)]
         stats: bool,
     },
-    /// Migrate transcript stub nodes to progress log
-    #[command(name = "migrate-transcript-progress")]
-    MigrateTranscriptProgress,
 }
 
 /// Print help with subcommands expanded to show nested commands.
@@ -464,15 +453,7 @@ impl Run for AdminCmd {
             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::Export { files, all } => cli::admin::cmd_export(&files, all).await,
             Self::LoadContext { stats } => cli::node::cmd_load_context(stats).await,
-            Self::MigrateTranscriptProgress => {
-                let arc = hippocampus::access_local()?;
-                let mut store = arc.lock().await;
-                let count = store.migrate_transcript_progress()?;
-                println!("Migrated {} transcript segment markers", count);
-                Ok(())
-            }
         }
     }
 }