refactor: Remove dead code in openrouter.rs content truncation

[AlexMikhalev]

Issue Description

Content truncation logic in openrouter.rs is unreachable due to an early return check.

Location

crates/terraphim_service/src/openrouter.rs:168-172

Current Code

```rust
// Line 156: Early return if content too long
if content.len() > MAX_CONTENT_LENGTH {
return Err(...);
}

// Line 168-172: Unreachable truncation logic
let truncated_content = if content.len() > MAX_CONTENT_LENGTH {
&content[..MAX_CONTENT_LENGTH]
} else {
content
};
```

Impact

• MEDIUM priority - Dead code
• Confusing for maintainers
• Wastes compilation time

Recommended Fix

Either:

1. Remove the early return to allow truncation
2. Remove the truncation logic entirely

References

• Identified in code review for PR fix(zipsign): update zipsign API to v0.2 #429
• Related to OpenRouter LLM integration