feat(resolve): parameter-type inference for instance method calls

- LanguageBehavior::extract_parameter_type returns the caller-parameter type from the function signature; Rust impl via tree-sitter AST descent (handles ref, lifetime, mut, generic, scoped)
- both Found and Ambiguous arms of resolve_one gated by inferred receiver type; zero-survivor returns NotFound (parity with story 2 slice 6 spec correction)
- caller signature is the type source; bypasses per-parser SymbolKind::Parameter emission (today only C/C++/Go/Lua emit Parameter)
- LanguageBehavior::self_receiver_aliases lifts the hardcoded "self" literal at resolve_method_call; overrides for PHP $this, Python self/cls, JS/TS/Java/Kotlin/C++ this
- PHP LanguageBehavior::is_receiver_compatible strips $ prefix, resolves $this to caller class
- C# is_static fires on leading-uppercase Pascal receivers; C++ method-call extraction threads caller-context
- self-index resolved count 23637 -> 22914 (-723) from wrong-class single-candidate matches collapsing to NotFound; Go extract_calls_recursive now resolves 2 callees (extract_function_name + self-recursion)
- slice 4.6 codified as gate-behavior integration tests per "NO Indexing in tests/" convention