Support quoted image paths and preserve prompt in CLI image command

[nordicnode]

Support quoted image paths and preserve prompt in CLI image command

Summary

• Fixes /image <path> [message] command parsing in the CLI to properly handle quoted paths ("..." and '...') and backslash-escaped spaces (\ ).
• Previously, args.trim().split(/\s+/) broke paths with spaces (common for screenshots on macOS/Windows) into separate tokens, corrupting the image filename (e.g. "/path/to/my causing a file-not-found error) and leaking the remainder into the message.
• Extracts parseImageCommandArgs into a standalone, pure utility (cli/src/commands/parse-image-args.ts) that correctly isolates the image path from the accompanying message.
• In cli/src/commands/command-registry.ts, preserves any returned prompt message in params.setInputValue so the user's instructions are retained in the input field alongside the attached image rather than being wiped by clearInput(params).
• Replaces the duplicated test parser in cli/src/commands/__tests__/image.test.ts with the real utility and adds unit test cases for quoted paths with spaces, escaped spaces, and quote edge cases.

Test plan

[✓] bun test --config=/dev/null src/commands/__tests__/image.test.ts — 16 pass, 0 fail (added tests for double/single quoted paths with spaces, escaped spaces, and prompt retention)
[✓] bun run --cwd cli typecheck — 0 errors
[✓] PR hygiene checks pass cleanly

[codebuff-team]

Good find and a clean fix. The old args.trim().split(/\s+/) in image.ts genuinely broke on macOS/Windows screenshot filenames containing spaces (e.g. Screenshot 2026-09-02 at 10.00.00.png), and the remaining message returned from handleImageCommand was previously discarded in command-registry.ts via clearInput(params) regardless of content — so this is a real bug fix, not just refactoring.

The extraction into parse-image-args.ts is sensible, and the tests in image.test.ts cover the interesting cases: double/single quotes, escaped spaces, empty quotes, quoted-path-only. Nice touch testing "" please analyze this returning null.

A few things worth double-checking before this lands:

• Unclosed quotes ("path with no closing quote) fall through silently to the escaped-space branch and treat the leading " as a literal path character — probably fine, but worth a test case documenting the intended behavior.
• Quote handling doesn't verify anything follows the closing quote besides whitespace, so "path"extra would produce message = 'extra' glued oddly, but this is a minor edge case.
• No unescaping for backslash-escaped quote characters inside a quoted path, but that's an acceptable scope limit for a first pass.

Small, in-scope, correctly tested — this looks portable as-is.