refactor(search): rename --after/--updated-after to --since/--updated-since

The --since naming is more intuitive (matches git log --since) and
consistent with the list commands which already use --since. Renames
the CLI flags, SearchCliFilters fields, SearchFilters fields,
autocorrect registry, and robot-docs manifest. No behavioral change.

Affected paths:
- cli/mod.rs: SearchArgs field + clap attribute rename
- cli/commands/search.rs: SearchCliFilters + run_search plumbing
- search/filters.rs: SearchFilters struct + apply_filters logic
- main.rs: handle_search + robot-docs JSON
- cli/autocorrect.rs: COMMAND_FLAGS entry for search

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/search/filters.rs

@@ -16,8 +16,8 @@ pub struct SearchFilters {
     pub source_type: Option<SourceType>,
     pub author: Option<String>,
     pub project_id: Option<i64>,
-    pub after: Option<i64>,
-    pub updated_after: Option<i64>,
+    pub since: Option<i64>,
+    pub updated_since: Option<i64>,
     pub labels: Vec<String>,
     pub path: Option<PathFilter>,
     pub limit: usize,
@@ -28,8 +28,8 @@ impl SearchFilters {
         self.source_type.is_some()
             || self.author.is_some()
             || self.project_id.is_some()
-            || self.after.is_some()
-            || self.updated_after.is_some()
+            || self.since.is_some()
+            || self.updated_since.is_some()
             || !self.labels.is_empty()
             || self.path.is_some()
     }
@@ -85,15 +85,15 @@ pub fn apply_filters(
         param_idx += 1;
     }
 
-    if let Some(after) = filters.after {
+    if let Some(since) = filters.since {
         sql.push_str(&format!(" AND d.created_at >= ?{}", param_idx));
-        params.push(Box::new(after));
+        params.push(Box::new(since));
         param_idx += 1;
     }
 
-    if let Some(updated_after) = filters.updated_after {
+    if let Some(updated_since) = filters.updated_since {
         sql.push_str(&format!(" AND d.updated_at >= ?{}", param_idx));
-        params.push(Box::new(updated_after));
+        params.push(Box::new(updated_since));
         param_idx += 1;
     }