digest: split into focused modules, externalize prompts

digest.rs was 2328 lines containing 6 distinct subsystems. Split into:
- llm.rs: shared LLM utilities (call_sonnet, parse_json_response, semantic_keys)
- audit.rs: link quality audit with parallel Sonnet batching
- enrich.rs: journal enrichment + experience mining
- consolidate.rs: consolidation pipeline + apply

Externalized all inline prompts to prompts/*.md templates using
neuro::load_prompt with {{PLACEHOLDER}} syntax:
- daily-digest.md, weekly-digest.md, monthly-digest.md
- experience.md, journal-enrich.md, consolidation.md

digest.rs retains temporal digest generation (daily/weekly/monthly/auto)
and date helpers. ~940 lines, down from 2328.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

src/main.rs

@@ -14,7 +14,11 @@
 // interference detection, schema assimilation, reconsolidation.
 
 mod store;
+mod llm;
 mod digest;
+mod audit;
+mod enrich;
+mod consolidate;
 mod graph;
 mod search;
 mod similarity;
@@ -516,7 +520,7 @@ fn cmd_consolidate_session() -> Result<(), String> {
 
 fn cmd_consolidate_full() -> Result<(), String> {
     let mut store = store::Store::load()?;
-    digest::consolidate_full(&mut store)
+    consolidate::consolidate_full(&mut store)
 }
 
 fn cmd_triangle_close(args: &[String]) -> Result<(), String> {
@@ -824,7 +828,7 @@ fn cmd_journal_enrich(args: &[String]) -> Result<(), String> {
     }
 
     let mut store = store::Store::load()?;
-    digest::journal_enrich(&mut store, jsonl_path, entry_text, grep_line)
+    enrich::journal_enrich(&mut store, jsonl_path, entry_text, grep_line)
 }
 
 fn cmd_experience_mine(args: &[String]) -> Result<(), String> {
@@ -840,7 +844,7 @@ fn cmd_experience_mine(args: &[String]) -> Result<(), String> {
     }
 
     let mut store = store::Store::load()?;
-    let count = digest::experience_mine(&mut store, &jsonl_path)?;
+    let count = enrich::experience_mine(&mut store, &jsonl_path)?;
     println!("Done: {} new entries mined.", count);
     Ok(())
 }
@@ -852,7 +856,7 @@ fn cmd_apply_consolidation(args: &[String]) -> Result<(), String> {
         .map(|w| w[1].as_str());
 
     let mut store = store::Store::load()?;
-    digest::apply_consolidation(&mut store, do_apply, report_file)
+    consolidate::apply_consolidation(&mut store, do_apply, report_file)
 }
 
 fn cmd_differentiate(args: &[String]) -> Result<(), String> {
@@ -919,7 +923,7 @@ fn cmd_differentiate(args: &[String]) -> Result<(), String> {
 fn cmd_link_audit(args: &[String]) -> Result<(), String> {
     let apply = args.iter().any(|a| a == "--apply");
     let mut store = store::Store::load()?;
-    let stats = digest::link_audit(&mut store, apply)?;
+    let stats = audit::link_audit(&mut store, apply)?;
     println!("\n{}", "=".repeat(60));
     println!("Link audit complete:");
     println!("  Kept: {}  Deleted: {}  Retargeted: {}  Weakened: {}  Strengthened: {}  Errors: {}",