feat: add LSP usage guidelines and operations table

.claude/rules/lsp.md

@@ -0,0 +1,24 @@
+# LSP Usage
+
+The `LSP` tool provides TypeScript-aware code intelligence. Prefer it over `grep`/`find` for symbol-level queries.
+
+## When to use LSP (not grep)
+
+| Task | LSP operation |
+|------|--------------|
+| Find where a function/class/type is defined | `goToDefinition` |
+| Find all call sites of a function | `findReferences` |
+| Check a variable's type or JSDoc | `hover` |
+| List all exports in a file | `documentSymbol` |
+| Find what implements an interface | `goToImplementation` |
+| Trace who calls a function | `incomingCalls` |
+| Trace what a function calls | `outgoingCalls` |
+
+## Decision rule
+
+- **Use LSP** when the query is about a *symbol* (function, class, type, variable) — LSP understands TypeScript semantics and won't false-match string occurrences.
+- **Use grep** when searching for string literals, comments, config values, or when LSP returns no results (e.g., generated code, `.js` files without types).
+
+## Required: line + character
+
+LSP operations require `line` and `character` (both 1-based). Read the file first to identify the exact position of the symbol, then call LSP.