[Feature] Add client config option to ignore corrupted local offset files instead of throwing exception

### Is Your Feature Request Related to a Problem?

When ~/.rocketmq_offsets/ files are corrupted (e.g., truncated due to power loss during persistAll()), readLocalOffsetBak() unconditionally throws MQClientException, which prevents the consumer from starting and crashes the entire application. The error "maybe fastjson version too low" is misleading — the real cause is file corruption, not a version issue.

For applications that already rely on CONSUME_FROM_TIMESTAMP, the persistent offset is non-critical — losing it does not affect data correctness. But there is currently no way to tell RocketMQ "just ignore corrupted offset files and start fresh."

### Describe the Solution You'd Like

Add a client configuration property, e.g.:

```
# Default false — keep existing behavior (throw on corruption)
rocketmq.client.localOffsetStore.ignoreCorrupted=false
```

When set to true, readLocalOffsetBak() should return null instead of throwing when JSON parsing fails:

```
private OffsetSerializeWrapper readLocalOffsetBak() throws MQClientException {
// ...
if (content != null && content.length() > 0) {
try {
offsetSerializeWrapper = OffsetSerializeWrapper.fromJson(content, ...);
} catch (Exception e) {
log.warn("readLocalOffset Exception", e);
if (ignoreCorrupted) {
return null;
}
throw new MQClientException("readLocalOffset Exception, ...", e);
}
}
return null;
}
```

When ignoreCorrupted=true and offset files are corrupted, load() starts with an empty offset table, and the consumer falls back to CONSUME_FROM_TIMESTAMP (or the latest message if no timestamp is set). Behavior only differs from the default on startup after file corruption —normal operation is unaffected.

### Describe Alternatives You've Considered

- Always return null (no config): Too aggressive — changes default behavior for all existing users who may depend on the exception for fast-fail
semantics.
- Application-level workaround: Manually delete ~/.rocketmq_offsets/ before each consumer start. Effective but fragile — requires every affected
application to implement its own cleanup logic. A built-in opt-in config is cleaner and discoverable.
- System property -Drocketmq.client.localOffsetStoreDir to a tmpfs: Redirects offsets to volatile storage, avoiding persistence entirely. Works but
throws away offsets for all consumers globally, which may be undesirable in mixed-use cases.

### Additional Context

_No response_

Start at the readLocalOffsetBak() and load() entry points described in the issue, then trace how the local offset configuration is read. Add the opt-in ignoreCorrupted setting with a default of false; done means corrupted offset JSON returns an empty offset table only when enabled, allowing CONSUME_FROM_TIMESTAMP fallback while preserving the existing exception by default.

Written by the indexing model from the issue text.