fix: Jira error deserialization, Connection header, and exit codes

[kolatts]

Summary

• Jira 400 error details lost: The parser was checking parsed.errors?.[0]?.message (array indexing) but Jira returns errors as a Record<string, string> and errorMessages as string[] — users were only ever seeing "HTTP 400 Bad Request". Now both fields are read and joined into a readable message.
• Connection: close header: Added to both jiraHeaders() and bitbucketHeaders() in src/lib/http.ts.
• Standard exit codes: New src/lib/exitCodes.ts with sysexits-style constants (GENERAL_ERROR=1, NETWORK_ERROR=69, AUTH_ERROR=77, CONFIG_ERROR=78). fail() in output.ts now maps HTTP 401/403 → 77 and network failures (status 0) → 69. All hardcoded process.exit(0)/process.exit(1) literals replaced with named constants.

Test plan

• npm run typecheck passes
• npm run lint passes
• npm run build passes
• Jira 400 response (e.g. missing required field) shows field-level error detail instead of generic "HTTP 400 Bad Request"
• Auth failure (401/403) exits with code 77: pncli jira issue get TEST-1; echo $?
• Network failure exits with code 69

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR improves pncli’s HTTP error reporting (notably for Jira 400 responses), standardizes process exit codes across the CLI, and tweaks default HTTP headers for Jira/Bitbucket requests.

Changes:

• Improve Jira error deserialization by extracting messages from errorMessages and field-level errors.
• Add Connection: close to Jira/Bitbucket request headers.
• Introduce ExitCode constants + HTTP-status→exit-code mapping, and replace hardcoded process.exit(0|1) calls.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/services/config/commands.ts	Replaces literal exit codes with ExitCode constants for abort/cancel paths.
src/lib/output.ts	Routes fail() exits through exitCodeFromStatus() for auth/network failures.
src/lib/http.ts	Enhances non-OK response parsing (Jira formats) and adds Connection: close headers; updates dry-run exit code.
src/lib/exitCodes.ts	Adds shared exit code constants and status→exit mapping helper.
src/cli.ts	Replaces fatal error exit literal with ExitCode.GENERAL_ERROR.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The new error-message extraction handles Jira’s errors as an object, but it no longer handles the previously-supported shape where errors is an array of objects with a message field (common in several APIs, and this file previously checked parsed.errors?.[0]?.message). This can regress error detail for those responses. Consider adding a branch for Array.isArray(parsed.errors) that pulls message (and/or joins multiple messages) before falling back to parsed.message.

[Copilot]

exitCodeFromStatus is currently typed to return number, which loses the stronger ExitCode union and makes it easier to accidentally return an out-of-range value later. Consider changing the return type to ExitCode (and optionally constraining the parameter to number) so callers like fail() stay type-safe.

Suggested change

	export function exitCodeFromStatus(httpStatus: number): number {
	export function exitCodeFromStatus(httpStatus: number): ExitCode {