docs: Update README and AGENTS.md with new features and options

README.md:
- Add cross-reference tracking feature description
- Add resource event history feature description
- Add observability feature description (verbosity, JSON logs, metrics)
- Document --no-events flag for sync command
- Add sync timing/progress bar behavior note
- Document verbosity flags (-v, -vv, -vvv)
- Document --log-format json option
- Add new database tables to schema reference:
  - resource_state_events
  - resource_label_events
  - resource_milestone_events
  - entity_references

AGENTS.md:
- Add --no-events example for sync command
- Document verbosity flags (-v, -vv, -vvv)
- Document --log-format json option

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

AGENTS.md

@@ -633,6 +633,9 @@ lore --robot status
 # Run full sync pipeline
 lore --robot sync
 
+# Run sync without resource events
+lore --robot sync --no-events
+
 # Run ingestion only
 lore --robot ingest issues
 
@@ -712,6 +715,8 @@ Errors return structured JSON to stderr:
 - Use `-n` / `--limit` to control response size
 - Use `-q` / `--quiet` to suppress progress bars and non-essential output
 - Use `--color never` in non-TTY automation for ANSI-free output
+- Use `-v` / `-vv` / `-vvv` for increasing verbosity (debug/trace logging)
+- Use `--log-format json` for machine-readable log output to stderr
 - TTY detection handles piped commands automatically
 - Use `lore --robot health` as a fast pre-flight check before queries
 - The `-p` flag supports fuzzy project matching (suffix and substring)