feat: Add PEP 750 template string support

[koxudaxi]

Adds parsing support for PEP 750 Template Strings, a new Python 3.14 feature that introduces t-strings for safer templating.

Overview

Template strings use the t prefix and create Template objects instead of regular strings, enabling secure HTML/SQL templating and DSL support:

# Basic template string
name = "world"
template = t"Hello, {name}!"

# Multi-line with format specifiers
html = t"""
<div class="user">
    <h1>{user.name}</h1>
    <p>Score: {score:04d}</p>
</div>
"""

Changes

• Added Template flag to scanner for t-prefixed string literals
• Extended scanner to recognize t/T prefixes (supports tr/rt combinations)
• Template strings reuse existing f-string interpolation mechanism
• Added comprehensive test coverage with 8 test cases

Related

• PEP: PEP 750 – Template Strings(https://peps.python.org/pep-0750/)
• Documentation: What's New in Python 3.14(https://docs.python.org/3.14/whatsnew/3.14.html#whatsnew314-pep750)
• CPython: Issue #132661(Implement PEP 750 – Template Strings python/cpython#132661)
• Community Tools: t-linter - syntax highlighting tool for template strings (by @koxudaxi) - GitHub | PyPI | VS Code Extension

Template strings will be available in Python 3.14.0b1+ and officially released in Python 3.14.