ops: add core backtrace helper

docs/server-management.md

@@ -47,6 +47,7 @@ The Debian deployment installs:
 - restarting the whole stack or specific channels/instances
 - viewing logs
 - listing core files in the runtime tree
+- generating a backtrace for the newest or selected core file
 - collecting incident bundles
 - running the root-only headless healthcheck
 - waiting for login-ready state after restart
@@ -185,6 +186,18 @@ List core files currently present in the runtime tree:
 metinctl cores
 ```
 
+Generate a backtrace for the newest core file:
+
+```bash
+metinctl backtrace
+```
+
+Generate a backtrace for one specific core file:
+
+```bash
+metinctl backtrace --core channels/channel1/core1/core.2255450
+```
+
 Collect an incident bundle with logs, unit status, port state and repository revisions:
 
 ```bash
@@ -214,6 +227,7 @@ This makes channel enablement declarative instead of depending on whatever happe
 The Debian deployment now also installs:
 
 - `/usr/local/sbin/metin-collect-incident`
+- `/usr/local/sbin/metin-core-backtrace`
 
 The collector creates a timestamped bundle under:
 
@@ -231,3 +245,11 @@ Each bundle contains:
 If you call it with `--include-cores`, matching core files are copied into the bundle as well.
 
 The runtime units now also declare `LimitCORE=infinity`, so after the next service restart the processes are allowed to emit core dumps when the host kernel/core policy permits it.
+
+For quick manual crash triage outside the incident bundle flow, use:
+
+```bash
+metinctl backtrace
+```
+
+It defaults to the newest core file under the runtime tree, infers the executable path, and uses `gdb` or `lldb` when present on the host. If no supported debugger is installed, it still prints file/readelf metadata for the core and executable.