fix(logging): reduce file log level to info and cut retention to 7 days

File logging was set to DEBUG level unconditionally, causing log files to
grow to 25-32GB each (200GB total across 8 files). The primary volume
came from per-HTTP-request, per-entity, and per-chunk debug!() calls in
the ingestion orchestrator, GitLab client, and embedding pipeline — all
of which wrote JSON events to daily-rotated log files regardless of CLI
verbosity flags.

Two changes:
- File filter: lore=debug,warn -> lore=info (eliminates ~90% of volume)
- Default retention: 30 days -> 7 days (caps total disk usage)

The info level still captures operational events (sync start/complete,
rate limits, errors, embedding progress) while per-request instrumentation
stays silent unless explicitly enabled via -vv/-vvv on stderr.

src/core/config.rs

@@ -175,7 +175,7 @@ pub struct LoggingConfig {
 }
 
 fn default_retention_days() -> u32 {
-    30
+    7
 }
 
 fn default_file_logging() -> bool {

src/core/logging.rs

@@ -65,7 +65,7 @@ pub fn build_file_filter() -> EnvFilter {
         return EnvFilter::from_default_env();
     }
 
-    EnvFilter::new("lore=debug,warn")
+    EnvFilter::new("lore=info")
 }
 
 pub fn cleanup_old_logs(log_dir: &Path, retention_days: u32) -> usize {