feat(config): Add fetchResourceEvents config flag with --no-events CLI override

Adds a new boolean field to SyncConfig that controls whether resource
event fetching is performed during sync:

- SyncConfig.fetch_resource_events: defaults to true via serde
  default_true helper, serialized as "fetchResourceEvents" in JSON
- SyncArgs.no_events: --no-events CLI flag that overrides the config
  value to false when present
- SyncOptions.no_events: propagates the flag through the sync pipeline
- handle_sync_cmd: mutates loaded config when --no-events is set,
  ensuring the flag takes effect regardless of config file contents

This follows the existing pattern established by --no-embed and
--no-docs flags, where CLI flags override config file defaults.
The config is loaded as mutable specifically to support this override.

Also adds "events" to the count command's entity type value_parser,
enabling `lore count events` (implementation in a separate commit).

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/cli/mod.rs

@@ -478,6 +478,10 @@ pub struct SyncArgs {
     /// Skip document regeneration
     #[arg(long)]
     pub no_docs: bool,
+
+    /// Skip resource event fetching (overrides config)
+    #[arg(long = "no-events")]
+    pub no_events: bool,
 }
 
 /// Arguments for `lore embed`
@@ -501,8 +505,8 @@ pub struct EmbedArgs {
 /// Arguments for `lore count <ENTITY>`
 #[derive(Parser)]
 pub struct CountArgs {
-    /// Entity type to count (issues, mrs, discussions, notes)
-    #[arg(value_parser = ["issues", "mrs", "discussions", "notes"])]
+    /// Entity type to count (issues, mrs, discussions, notes, events)
+    #[arg(value_parser = ["issues", "mrs", "discussions", "notes", "events"])]
     pub entity: String,
 
     /// Parent type filter: issue or mr (for discussions/notes)