chore: enable the perflint and comprehension ruff rules

[cloudsmith-iduffy]

Description

Ruff can catch a handful of slow Python patterns for us, so this turns on two of its rule groups:

• perflint (PERF) — flags loop patterns that do more work than they need to, like building a list with .append() in a loop when a comprehension would do
• flake8-comprehensions (C4) — flags unnecessary or roundabout comprehensions, like wrapping something in a list comprehension that's already a list

Then it fixes everything they flagged: mostly table-building loops in the list, repos, dependencies and download commands rewritten as comprehensions, a couple of hand-rolled dicts replaced with dict.fromkeys() / a dict comprehension, and one comprehension that was a no-op deleted outright.

To be honest about the motivation: none of these rewrites make the CLI measurably faster today — they're microseconds on loops of ~30 rows, so there are no flame graphs or benchmarks here. The point is the guard. The credential helpers now run on every docker/npm request, and I'd rather have the linter shout before an accidentally slow loop lands in one of those paths than find it in a profile later. Both rules run in pre-commit and in CI via the existing ruff hook, so there's nothing new to set up.

One rule from the group is deliberately switched off: try/except inside a loop. All four places it flagged use the except as actual control flow — for example the credential chain trying each provider in turn and moving on when one fails. Restructuring those to save nanoseconds would make the code worse.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactoring
• Other (please describe)

[Copilot]

Pull request overview

This pull request enables Ruff’s C4 and PERF rules and applies collection-building refactors across the CLI and core code.

Changes:

• Enables C4 and PERF, excluding intentional PERF203 cases.
• Replaces manual list and dictionary construction with comprehensions and dict.fromkeys().
• Removes redundant comprehensions.

Blocking findings:

• Critical: Remaining PERF401 violations exist in check.py and mcp.py.
• Critical: Remaining PERF403 violations exist in cloudsmith_cli/core/mcp/server.py.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Summary
pyproject.toml	Updates Ruff rule configuration; critical lint violations remain.
packaging/pyinstaller/entry.py	Simplifies keyring failure collection.
cloudsmith_cli/credential_helpers/docker/installer.py	Refactors action collection.
cloudsmith_cli/core/download.py	Uses a filtering comprehension.
cloudsmith_cli/core/api/vulnerabilities.py	Simplifies table and count construction.
cloudsmith_cli/core/api/packages.py	Simplifies payload and default dictionary creation.
cloudsmith_cli/cli/table.py	Removes a redundant comprehension.
cloudsmith_cli/cli/config.py	Simplifies config path construction.
cloudsmith_cli/cli/commands/repos.py	Uses a table-row comprehension.
cloudsmith_cli/cli/commands/list_.py	Uses a package-row comprehension.
cloudsmith_cli/cli/commands/download.py	Uses an item comprehension.
cloudsmith_cli/cli/commands/dependencies.py	Uses a dependency-row comprehension.

Suppressed comments (1)

cloudsmith_cli/cli/table.py:25

• This assignment is immediately overwritten by the initialization at line 42, so the new comprehension still calls str and strip_ansi for every row and discards the result. Removing only the outer no-op comprehension did not remove the dead work; delete this precomputation (and the similarly overwritten plain_headers assignment above) instead.

    plain_rows = [strip_ansi(str(v)) for v in rows]

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