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/cli/mod.rs

@@ -10,6 +10,11 @@ use std::io::IsTerminal;
 #[command(name = "lore")]
 #[command(version = env!("LORE_VERSION"), about = "Local GitLab data management with semantic search", long_about = None)]
 #[command(subcommand_required = false)]
+#[command(after_long_help = "\x1b[1mEnvironment:\x1b[0m
+  GITLAB_TOKEN       GitLab personal access token (or name set in config)
+  LORE_ROBOT         Enable robot/JSON mode (non-empty, non-zero value)
+  LORE_CONFIG_PATH   Override config file location
+  NO_COLOR           Disable color output (any non-empty value)")]
 pub struct Cli {
     /// Path to config file
     #[arg(short = 'c', long, global = true, help = "Path to config file")]
@@ -541,13 +546,13 @@ pub struct SearchArgs {
     #[arg(long, help_heading = "Filters")]
     pub path: Option<String>,
 
-    /// Filter by created after (7d, 2w, or YYYY-MM-DD)
+    /// Filter by created since (7d, 2w, or YYYY-MM-DD)
     #[arg(long, help_heading = "Filters")]
-    pub after: Option<String>,
+    pub since: Option<String>,
 
-    /// Filter by updated after (7d, 2w, or YYYY-MM-DD)
-    #[arg(long = "updated-after", help_heading = "Filters")]
-    pub updated_after: Option<String>,
+    /// Filter by updated since (7d, 2w, or YYYY-MM-DD)
+    #[arg(long = "updated-since", help_heading = "Filters")]
+    pub updated_since: Option<String>,
 
     /// Maximum results (default 20, max 100)
     #[arg(