chore: ruff auto-fix F541 — f-string-missing-placeholders

[wesleysimplicio]

What does this PR do?

Adds the F541 rule to pyproject.toml and applies auto-fix across 63 files.

Converts f-strings with no placeholder expressions — f"hello" → "hello" — since they execute the placeholder-expansion machinery for nothing.

Root cause

F-strings without {...} placeholders are syntactically valid but waste a format-call and are invisible bugs waiting to happen: a future editor adding {var} where the f prefix is missing gets a plain string instead of the expected interpolation. Making them an error keeps the codebase consistent.

Fix

• Added F541 to [tool.ruff.lint] select in pyproject.toml.
• Ran ruff check --select F541 --preview --fix . — 198 errors fixed across 63 files.

Why this shape

This is the same per-rule pattern used in the existing ruff PRs (#31825–#32027): enable one rule, auto-fix, commit. Separating rules keeps the diff focused and the blame history clean.

Tests

• ruff check passes with zero errors after the fix (rule is active in config).
• No runtime behaviour changed — only syntactic transformations.
• Existing pytest suite continues to pass.

Related PRs / issues

• Part of the ongoing ruff rule enablement campaign.
• No competing PRs found for F541.

[Morad37]

Clean auto-fix pass. The f\"...\" strings without placeholders are a common lint catch after refactors where a variable was inlined or removed. The F541 rule exists precisely for this -- saves readers a second of "wait, is there a substitution I'm missing?" on every read.

[austinpickett]

See consolidation note on #42036 — these four ruff PRs overlap and should be combined into one before merging.

[wesleysimplicio]

Closing in favor of consolidated PR (per austinpickett's request on #42036 — combining all four ruff PRs into one.)