[feat]: Make the random branch suffix optional #1936

Feature Summary

A per-project setting in .emdash.json to make the random 5-character branch suffix optional, so teams whose convention is one ticket ID → one branch name can use clean names like ZN-6671 instead of ZN-6671-aj3jg.

Problem or Use Case

Task branches always get a 5-character random suffix appended (e.g., ZN-6671-aj3jg). For teams that follow strict ticket-to-branch naming conventions (JIRA, Shortcut, Plane, etc.), this breaks the convention and requires a manual rename before every push.

We name tasks after JIRA ticket IDs (ZN-6671) so the branch matches the ticket. Our CI auto-links PRs, runs status checks, and routes deploys based on the ticket-key prefix in the branch name. The current suffix breaks all of these unless we manually rename before each push.

The suffix is hardcoded — there's no setting in .emdash.json or the UI:

src/main/core/tasks/operations/createTask.ts:46:

const suffix = Math.random().toString(36).slice(2, 7);

src/main/core/tasks/resolveTaskBranchName.ts:

return branchPrefix ? \`\${branchPrefix}/\${rawBranch}-\${suffix}\` : \`\${rawBranch}-\${suffix}\`;

The only existing escape is the Linear-linked-issue path (linkedIssue?.provider === 'linear'), which doesn't help users on JIRA, Shortcut, Plane, or other trackers.

Proposed Solution

A per-project setting in .emdash.json:

Option A — boolean, simplest:

{ "branchSuffix": false }

Option B — mode, preserves the existing uniqueness safety net:

{ "branchSuffix": "always" | "on-conflict" | "never" }

"on-conflict" would only append a suffix if the desired branch name already exists locally, so duplicate task names still don't clobber each other but the common case stays clean.

I'd advocate for Option B with "always" as the default for full backward compatibility.

Touchpoints in code:

• src/main/core/settings/schema.ts — new optional field on the project settings schema
• src/main/core/tasks/resolveTaskBranchName.ts — consume the new setting
• src/main/core/tasks/operations/createTask.ts:46 — suffix generation becomes conditional
• src/main/core/tasks/operations/renameTask.ts — same logic applies to renames

Alternatives Considered

Manual rename before push:

git branch -m ZN-6671-aj3jg ZN-6671
git push -u origin ZN-6671

Functional but doesn't scale across many tasks and developers.

A custom workspaceProvider script could replace emdash's worktree creation entirely, but that means reimplementing port assignment and integration logic for what is ultimately a cosmetic concern.

Additional Context

Happy to put up a PR if the maintainers are open to the direction.