Fix starboard embed SyntaxError and tighten flake8 linting

[youngcoder45]

This PR fixes a flake8-blocking SyntaxError in the Starboard embed formatter and adds a repository-level flake8 configuration so linting focuses on project code (and doesn’t scan the local virtualenv).

What Changed

• Starboard embed quoting
  • Fixes E999 SyntaxError: f-string expression part cannot include a backslash by moving the newline replacement out of the f-string expression.
  • Keeps the exact same rendered output for multi-line messages (still formats as a block quote).
• Coding questions utility
  • Fixes F824 by removing an incorrect global _question_pool declaration (the pool is mutated but never reassigned).
• Lint hygiene / cleanup
  • Adds .flake8 to exclude .venv, __pycache__, and build artifacts.
  • Removes a handful of unnecessary f-strings (F541) and unused locals (F841) without changing behavior (e.g., unused timers, unused exception variables).

Why

• flake8 was failing on:
  • a starboard f-string that performed content.replace('\n', ...) directly inside the f-string expression, and
  • an invalid global declaration in utils/codingquestions.py.
• flake8 runs were also noisy because they could traverse .venv and report third-party lint issues.

Testing

• python -m flake8 . --select=E999,F824,F541,F841 (passes)
• python -m flake8 . will still report existing style warnings (mostly E501/whitespace) in cogs/starboard.py that are out of scope for this PR.

Notes for Reviewers

• Changes are intended to be behavior-preserving aside from fixing the Starboard embed formatting crash.
• .flake8 only changes what gets linted; it doesn’t change runtime behavior.

[sinisterMage]

Looks good to me.