fix: handle missing prompts in commitlint config and OCO_ONE_LINE_COMMIT for split diffs

[octo-patch]

Problem

This PR fixes two bugs:

Bug 1 — Fixes #482: TypeError: Cannot read properties of undefined (reading 'join') with @commitlint

When the .opencommit-commitlint cache file exists but is missing the prompts field (e.g. generated by an older version of opencommit or manually edited), INIT_MAIN_PROMPT in src/modules/commitlint/prompts.ts crashes trying to call .join() on undefined.

Steps to reproduce:

oco config set OCO_PROMPT_MODULE=@commitlint
git add .
oco

Bug 2 — Fixes #474: OCO_ONE_LINE_COMMIT=true has no effect on large diffs

When a staged diff exceeds the context window it gets split into chunks, each generating its own commit message. These messages were then joined with \n\n, producing a multi-line result regardless of OCO_ONE_LINE_COMMIT=true.

Solution

Fix 1: After reading the cached commitlint config, check whether prompts is a valid array. If not (outdated/corrupted file), force a regeneration of the config before proceeding. This recovers gracefully instead of crashing.

Fix 2: When OCO_ONE_LINE_COMMIT is enabled and the diff was split into multiple chunks, extract the first line from each chunk's commit message and join them with '; ' to produce a single-line result.

Testing

• TypeScript typecheck passes (tsc --noEmit)
• Fix 1 is guarded by Array.isArray() so valid configs are not affected
• Fix 2 only activates when OCO_ONE_LINE_COMMIT=true and the diff was large enough to be split

[di-sukharev]

@octo-patch please fix the tests