refactor(cli): remove dead formatLogLine helper

[pedrofrxncx]

Net code reduction: -25 / +0.

formatLogLine (apps/api/src/cli/format-log-line.ts) was added in #3583 to tee intercepted console output into the deco link log file. The deco link CLI command and its log-teeing path have since been fully removed (there's no link subcommand left in apps/api/src/cli.ts, no startLinkDaemon, no link.log reference anywhere in the tree). formatLogLine was left behind with zero remaining callers — rg -n "formatLogLine" across the repo only turns up its own definition and its own test file.

This PR deletes the dead helper and its test.

How I confirmed behavior is unchanged: rg -n "formatLogLine" shows no other references anywhere in the repo (checked before deleting). Pure removal of unused code — nothing else calls it.

Reviewer check: rg -n "formatLogLine" on main should show the same two hits (definition + test) that this PR removes, and no other callers.

Locally verified: bun run fmt, cd apps/api && bunx tsc --noEmit (clean). No test to run since the deleted code had no other consumers — full CI covers the rest.

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Summary by cubic

Removes the dead formatLogLine helper and its test from the CLI; it was only used by the now-removed deco link log tee, so this has no runtime effect.

• No remaining callers: rg -n "formatLogLine" on main only finds the deleted definition and test.
• Confirms the deco link path is gone: no link subcommand, startLinkDaemon, or link.log references remain.
• Build stays clean: bun run fmt and bunx tsc --noEmit pass.
• No migration or rollout steps.

^{Written for commit 56f5866. Summary will update on new commits.}