Ruff should warn on all CPython SyntaxWarnings

### Summary

CPython emits a SyntaxWarning for certain code, but SyntaxWarnings have some issues that can make them difficult to reliably detect in CI (current discussion in [https://discuss.python.org/t/pep-765-disallow-return-break-continue-that-exit-a-finally-block/71348](discuss.python.org) about PEP 765). So it would be nice if Ruff could guarantee that it emits an error on any code for which CPython would produce a SyntaxWarning.

Here is a [playground link](https://play.ruff.rs/0437f5dd-3ea3-463c-b27e-71814287282e) covering all current SyntaxWarnings I could find in the CPython source code. Ruff already warns for most of them, though the logic may not always match exactly.

* Invalid numeric literals (e.g., `123or 1`) [lexer.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Parser/lexer/lexer.c#L346)
* Not implemented in Ruff. See [this thread](https://discuss.python.org/t/whats-going-on-with-syntaxwarning-invalid-decimal-literal/52694) and linked discussions for background.
* Invalid escape sequences in strings (e.g., `"\99"`) [string_parser.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Parser/string_parser.c#L47)
* Ruff W605. Might need auditing of the code to verify this matches the CPython logic exactly.
* Backslash next to `{` or `}` in f-strings or t-strings (e.g., `f"\{1}"`) ([lexer.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Parser/lexer/lexer.c#L1578))
* Also W605, but uses a different code path in CPython.
* Control flow in a `finally` block (see PEP 765) ([ast_preprocess.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/ast_preprocess.c#L71))
* Ruff B012.
* `is` / `is not` with a literal (`() is ()`) [codegen.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/codegen.c#L1836)
* Ruff F632.
* `assert` that is always true (`assert (1,)`) [codegen.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/codegen.c#L2951)
* Ruff F631.
* Calling something that definitely isn't callable (`{}()`) [codegen.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/codegen.c#L3650)
* Not implemented in Ruff. Type checkers will surely catch this (and more), but it may be valuable to add a rule specifically for the SyntaxWarning-triggering code here.
* Subscripting something that definitely is not subscriptable (`{1}[1]`) [codegen.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/codegen.c#L3679)
* Not implemented in Ruff; similar considerations to the last one.
* Using a wrong index type for some types (`"a"["b"]`) [codegen.c](https://github.com/python/cpython/blob/2a54acf3c3d9f388c3d878a17ea804a801affca9/Python/codegen.c#L3715)
* Ruff RUF016.

Start with the linked CPython lexer.c, string_parser.c, ast_preprocess.c, and codegen.c locations, then compare the existing Ruff rules W605, B012, F632, F631, and RUF016 against the playground examples. Review the missing invalid-literal, non-callable, and non-subscriptable cases and determine the coverage needed. Done means Ruff reliably reports every listed case with matching tests.

Written by the indexing model from the issue text.