Replace ct or ./dist/ct with deno task ct in docs

[bfollington]

Summary by cubic

Replaced all docs references to ct or ./dist/ct with deno task ct to standardize usage and remove the need to build a local binary. Also removed an outdated helper script that depended on ./dist/ct.

• Migration
  • Run commands as deno task ct [command].
  • Optional: alias ct="deno task ct" for convenience.
  • Removed .claude/page-manager-helper.sh as it relied on ./dist/ct.

^{Written for commit 01af315. Summary will update automatically on new commits.}

[linear]

CT-1023 Update documentation to prefer `deno task ct` over `./ct`

[cubic-dev-ai]

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