Restore missing CLI pages (and other misc improvements)

[guolau]

Affected Components

• Content & Marketing
• Pricing
• Test
• Docs
• Learn
• Other

Summary of changes

Content from these old docs ...	... was added back to the new docs here
/docs/cli/	/cli/overview Replaced the content that previously was on this page
/docs/cli/installation/ Sections: Prerequisites Installation Direct download Using a proxy server	/cli/installation
/docs/cli/installation/ Sections: Authentication	/cli/authentication
/constructs/dynamic-monitor-creation	/constructs/dynamic-monitor-creation
/docs/cli/project-structure/	/constructs/overview
/docs/cli/using-constructs/ Sections: Assigning Logical IDs	/constructs/overview
/docs/cli/using-git/	/cli/attaching-git-metadata
/docs/cli/npm-packages/	/cli/dependencies
/docs/cli/cli-vs-terraform-pulumi/	/cli/cli-vs-terraform-pulumi

• Added back Windsurf page since this was referenced in /cli/overview#using-ai-ides-and-copilots. Probably want to replace that tile with a more popular AI provider? Replaced it with Claude Code, since it's more popular
• Removed /docs/cli/basic-workflow/ as it looks to be unverified AI-gen content
• Refactored some stuff into reusable snippets: cli-env-vars and main-cicd-cards

Other notes

• /docs/cli/using-check-test-match/: already been brought over, so no changes were needed
• /docs/cli/using-environment-variables/: already brought over, no changes needed
• /docs/cli/constructs-reference/ and /docs/cli/command-line-reference/ were large pages, so I'm leaving those for another time
• When merging this PR, please also merge the redirects: https://github.com/checkly/checkly-marketing-website/pull/346

Ref: https://linear.app/checklyhq/issue/DOC-24/update-redirects-for-cli-urls-and-general-review-of-cli-pages