Move UTF-8 safety pattern from AGENTS.md to project memory

The UTF-8 string slicing pattern is better suited as a remembered
pattern in project memory rather than a static AGENTS.md section.
This keeps AGENTS.md focused on codebase-specific invariants while
the pattern remains accessible for reference.

Agent: g3

AGENTS.md

@@ -71,18 +71,6 @@
 - Different configs for interactive vs autonomous mode
 - **Risk**: Aggressive retries can hit rate limits harder
 
-### UTF-8 String Slicing (Throughout Codebase)
-
-- Rust string slices (`&s[..n]`) use **byte indices**, not character indices
-- Multi-byte UTF-8 characters (emoji, bullets `•`, `×`, `⚡`) cause panics if sliced mid-character
-- **Risk**: Runtime panic on any string containing non-ASCII characters
-- **Fix**: Use `char_indices()` to find byte boundaries:
-  ```rust
-  let byte_idx = s.char_indices().nth(char_limit).map(|(i, _)| i).unwrap_or(s.len());
-  let truncated = &s[..byte_idx];
-  ```
-- **Danger zones**: Display truncation, ACD stubs, user input handling
-
 ## Do's and Don'ts for Automated Changes
 
 ### Do
@@ -111,7 +99,6 @@
 3. **"Tool results are always small"** - File reads can return megabytes
 4. **"Sessions persist across runs"** - Sessions are ephemeral by default
 5. **"All platforms are equal"** - macOS has more features (Vision, Accessibility)
-6. **"String length equals character count"** - `s.len()` returns bytes; use `s.chars().count()` for characters
 
 ## Dependency Analysis Artifacts