Handle URL extension routes with redirects

[eyeseast]

• Bust cache and fix canonical link
• Add page handler for file extension routes

Closes #997 and #56

Test on this document: https://deploy-preview-1005.muckcloud.com/documents/20006908-lawsuit-document-dkt-1-68-ex-j/

• Embed: https://deploy-preview-1005.muckcloud.com/documents/20006908-lawsuit-document-dkt-1-68-ex-j.html
• Text: https://deploy-preview-1005.muckcloud.com/documents/20006908-lawsuit-document-dkt-1-68-ex-j.txt
• PDF: https://deploy-preview-1005.muckcloud.com/documents/20006908-lawsuit-document-dkt-1-68-ex-j.pdf
• Fallback https://deploy-preview-1005.muckcloud.com/documents/20006908-lawsuit-document-dkt-1-68-ex-j.lol

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[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	31.84%	7674 / 24099
🔵	Statements	31.84%	7674 / 24099
🔵	Functions	47.67%	339 / 711
🔵	Branches	75.66%	1113 / 1471

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/routes/(app)/documents/[id]-[slug]/+page.ts	0%	0%	0%	0%	1
src/routes/(app)/documents/[id]-[slug].[format]/+page.ts	0%	0%	0%	0%	1
src/routes/(app)/projects/[id]/+page.ts	0%	0%	0%	0%	1

Generated in workflow #567 for commit 77aaeac by the Vitest Coverage Report Action

[allanlasser]

This is a great approach! My only design question is whether .txt should redirect to the text mode in an embed viewer instead of the full-site viewer.

[eyeseast]

Historically, there wasn't a difference between embed and normal versions of the viewer (except in the very beginning), but the .html extension is baked into the WordPress plugin (by me, a long time ago, sorry) so it's still used in embeds.

This is the old documentation: https://web.archive.org/web/20180301171441/https://www.documentcloud.org/help/publishing#linking

All that said, I don't have much evidence of anyone using the .txt. or .pdf links, and it hasn't been supported in a few years, so I think we're ok like this, and we can adjust if needed.