docs: explain role of mise and Renovate, add editorconfig

[zeitlinger]

Summary

• Add "How it works" section to README explaining the role of mise
  (tool installer + task runner) and Renovate (dependency updater +
  preset) for users new to the project
• Add per-linter paragraphs describing how mise and Renovate interact
  with each task (super-linter, links, renovate-deps)
• Add .editorconfig with line length limits (100 default, 120 for
  scripts, 300 for config files) mirroring prom_client_java setup
• Wrap all README/CLAUDE.md prose to 100 chars, use
  editorconfig-checker-disable for tables and HTML that can't be
  shortened
• Extract long shell/Python lines into intermediate variables to
  comply with editorconfig limits

Test plan

• mise run lint passes locally
• CI passes on this PR
• Verify README renders correctly on GitHub (badges, tables, links)

[Copilot]

Pull request overview

This PR improves onboarding documentation for flint by explaining how mise (tool installer + task runner) and Renovate (dependency updater + preset) work together, and adds an .editorconfig to standardize line-length limits across the repo.

Changes:

• Expanded README with a “How it works” section and per-task explanations of how mise and Renovate interact.
• Wrapped prose to 100 chars, added editorconfig-checker-disable guards for sections that can’t reasonably conform (tables/HTML).
• Added .editorconfig line-length limits and refactored a few long lines in scripts/config.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tasks/lint/renovate-deps.py	Refactors env parsing into an intermediate variable to avoid long lines.
tasks/lint/links.sh	Extracts the default regex into a variable to reduce line length and improve readability.
README.md	Adds “How it works” + per-task mise/Renovate behavior; wraps prose and adds checker disable/enable markers.
CLAUDE.md	Wraps the AUTOFIX convention description to comply with line-length constraints.
.github/renovate.json5	Collapses long arrays/strings to reduce formatting noise and align with new line-length policies.
.editorconfig	Introduces repo-wide max line length rules (and indentation settings).

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