A repository name's rules and its disk-init failure live in one module, read by migrate, apps and new repository #5584

For: Making a repository, an app or a migration with a bad name reads the same wherever it is said, because it is said from one place. Today each sentence below is typed out separately in src/actions/migrate.ts, src/web/pages/apps.ts, src/web/pages/site.ts, so the next edit to one copy makes them drift.

Done:

• [ ] src/actions/repo_words.ts exports these sentences (new, or the existing module of that concept if one already owns similar words; say which in the pull):

- "Names start with a letter or digit; no spaces, no .git." - "The repository could not be initialised on disk."

• [ ] Every file named imports them, and grep -rn for each sentence under src/ finds only the module.
• [ ] Answers and pages are byte-for-byte unchanged: every existing test passes as it is.
• [ ] A new test/repo-words.test.ts asserts each exported sentence is non-empty and that each file named no longer contains the literal (read the source as text). It fails if a copy is typed back.
• [ ] Before pushing, run test/repo-words.test.ts, the tests of the files you touched, bun x tsc --noEmit and, if src/web changed, bun scripts/design-lint.ts. A red test elsewhere that main also has is named in the pull, not a reason to stop.

Files: src/actions/repo_words.ts, src/actions/migrate.ts, src/web/pages/apps.ts, src/web/pages/site.ts, test/repo-words.test.ts. Risk: a pure move; change no wording. Touch only the lines the sentences are on.