docs: clean up README examples, API table and footer

[lesnik512]

Summary

README fixes from a docs review.

• The Usage example imports were unsorted, and the Action scope example imported FromDI without using it and had an unused loop variable (ruff I001, F401, B007)
• The API list said FromDI(provider), but it accepts a provider or a type (modern_di_typer/main.py: FromDI = integrations.from_di); other integration READMEs call the argument dependency

Changes

• Sort example imports, drop the unused FromDI import, pass job_name to run(); both snippets pass ruff check and ruff format --check (undefined placeholder names aside)
• API section converted to the Symbol | Description table used by the other integrations; FromDI(dependency); action_scope(ctx) kept (exported from modern_di_typer/__init__.py)
• Used by: one plain sentence, same link targets
• Remove em dashes; shared footer: "with an IoC container", org link sentence without a dash

Checklist

• Lint and format pass (ruff)
• Type check passes (ty)
• Tests pass and new behavior is covered
• Build succeeds (uv build) if packaging or build config changed
• Repo metadata stays consistent across the three surfaces (GitHub description, pyproject description, profile blurb) if this touches packaging