docs: polish readme, update example.env, and gitignore

[nicokempe]

What kind of change does this PR introduce?

Docs update / configuration cleanup

What is the current behavior?

• README contained inconsistent wording, capitalization, and formatting.
• example.env provider sections weren’t fully normalized (e.g., brand naming).
• .idea IDE files were not ignored, risking accidental commits.

What is the new behavior?

• README polished for clarity and consistency (terminology, grammar, branding).
• example.env updated with cleaner provider sections and improved comments (e.g., explicit Twitter (X) naming).
• .gitignore updated to exclude .idea directories.
• Inherited features section: updated the outdated note on JWT signing. It now reflects current Supabase Auth behavior: asymmetric signing keys (RS256 by default, ECC/Ed25519 optional) are supported and recommended, while HS256 remains for compatibility.

Additional context

This PR improves documentation and developer ergonomics only. Read through the readme because I wanted to contribute to the project and just updated everything that didn't look right. No functional or runtime changes.

[cstockton]

Thanks!

[coveralls]

Pull Request Test Coverage Report for Build 17884019207

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 67.818%

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Totals
Change from base Build 17830497765:	0.0%
Covered Lines:	12935
Relevant Lines:	19073

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💛 - Coveralls