[test-recorder] Replace remaining developer jargon in human-path copy with plain language

### Problem
`guide.ts` bans jargon for supervised sessions (`src/commands/guide.ts:36-44`), but the human TTY path still emits developer terms a non-dev tester won't know: "branch", "checkout", `gh`, "commit", "dev server", "feature flags", "refactor", "Playwright conventions", "assert buttons" (`src/commands/record.ts:164-222,347-355,617-638,742-765,772`; `src/pr/openPr.ts:71-95`), and commit-failure copy mentions "pre-commit checks" and "assertions" (`src/pr/gh.ts:63-79`). Live user testing confirmed these terms confuse and scare non-technical users.

### Suggested fix
Audit all TTY-facing strings; replace dev terms with plain-language equivalents ("the version of the app you're testing", "checkpoint buttons", etc.); reserve technical detail for an expandable troubleshooting block or non-TTY output.

_Line references are against branch `cb/comfy-test-usability` (PR #15837); adjust after merge._