Remove .md suffix stripping from key lookups

The strip_md_suffix function was removed but its usages remained,
causing lookups like `identity.md` to fail (stripped to `identity`
which didn't exist). Now keys are used as-is.

Renamed 4 nodes that had .md suffixes to canonical form:
- identity.md → identity
- promotion-work-queue.md-* → promotion-work-queue-*
- patterns.md#* → patterns-*
- practices.md#* → practices-*

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

src/hippocampus/store/mod.rs

@@ -36,17 +36,6 @@ use redb::Database;
 use std::sync::atomic::AtomicU64;
 use std::sync::Mutex;
 
-/// Strip .md suffix from a key, handling both bare keys and section keys.
-/// "identity.md" → "identity", "foo.md#section" → "foo#section", "identity" → "identity"
-pub fn strip_md_suffix(key: &str) -> String {
-    if let Some((file, section)) = key.split_once('#') {
-        let bare = file.strip_suffix(".md").unwrap_or(file);
-        format!("{}#{}", bare, section)
-    } else {
-        key.strip_suffix(".md").unwrap_or(key).to_string()
-    }
-}
-
 // The full in-memory store with internal locking
 pub struct Store {
     /// Log sizes at load time — used for staleness detection.
@@ -167,11 +156,8 @@ impl Store {
     }
 
     pub fn resolve_key(&self, target: &str) -> Result<String> {
-        // Strip .md suffix if present — keys no longer use it
-        let bare = strip_md_suffix(target);
-
-        if self.contains_key(&bare)? {
-            return Ok(bare);
+        if self.contains_key(target)? {
+            return Ok(target.to_string());
         }
 
         let db = self.db.as_ref()