feat: centralized logging, instrumentation, hermes logs CLI, gateway noise fix (#5430)

Adds comprehensive logging infrastructure to Hermes Agent across 4 phases:

**Phase 1 — Centralized logging**
- New hermes_logging.py with idempotent setup_logging() used by CLI, gateway, and cron
- agent.log (INFO+) and errors.log (WARNING+) with RotatingFileHandler + RedactingFormatter
- config.yaml logging: section (level, max_size_mb, backup_count)
- All entry points wired (cli.py, main.py, gateway/run.py, run_agent.py)
- Fixed debug_helpers.py writing to ./logs/ instead of ~/.hermes/logs/

**Phase 2 — Event instrumentation**
- API calls: model, provider, tokens, latency, cache hit %
- Tool execution: name, duration, result size (both sequential + concurrent)
- Session lifecycle: turn start (session/model/provider/platform), compression (before/after)
- Credential pool: rotation events, exhaustion tracking

**Phase 3 — hermes logs CLI command**
- hermes logs / hermes logs -f / hermes logs errors / hermes logs gateway
- --level, --session, --since filters
- hermes logs list (file sizes + ages)

**Phase 4 — Gateway bug fix + noise reduction**
- fix: _async_flush_memories() called with wrong arg count — sessions never flushed
- Batched session expiry logs: 6 lines/cycle → 2 summary lines
- Added inbound message + response time logging

75 new tests, zero regressions on the full suite.

hermes_cli/config.py

@@ -537,6 +537,14 @@ DEFAULT_CONFIG = {
         "wrap_response": True,
     },
 
+    # Logging — controls file logging to ~/.hermes/logs/.
+    # agent.log captures INFO+ (all agent activity); errors.log captures WARNING+.
+    "logging": {
+        "level": "INFO",       # Minimum level for agent.log: DEBUG, INFO, WARNING
+        "max_size_mb": 5,      # Max size per log file before rotation
+        "backup_count": 3,     # Number of rotated backup files to keep
+    },
+
     # Config schema version - bump this when adding new required fields
     "_config_version": 12,
 }