DEVX-55: fix: revert squash-merge format to use colon after task ID

AGENTS.md

@@ -162,7 +162,7 @@ the PR. Then add the `ready-to-merge` label. The auto-merge workflow will:
 1. **Validate** PR title format (`DEVX-N: <vikunja task title>`) and match against Vikunja task title
 2. **Check** that at least one substantive APPROVE review exists
 3. Wait for all CI checks to pass (including the `pr-review` job)
-4. Squash-merge with title: `DEVX-N <conventional commit message>` (space-separated, no colon after DEVX-N)
+4. Squash-merge with title: `DEVX-N: <conventional commit message>`
 5. The post-merge workflow marks the Vikunja task as done
 6. The release workflow automatically versions, tags, and publishes
 
@@ -259,7 +259,7 @@ by `python -m devx.tools.install_tools` and configured by
 
 ### git-cliff Commit Preprocessing
 
-Merge commits on master have the format `DEVX-N <conventional commit>`. The
+Merge commits on master have the format `DEVX-N: <conventional commit>`. The
 `cliff.toml` includes a `commit_preprocessors` entry that strips the `DEVX-N `
 prefix before parsing. This ensures all merged work appears in the changelog.
 
@@ -282,7 +282,7 @@ setuptools via `dynamic = ["version"]` in `pyproject.toml`.
 | Branch name | `DEVX-N-short-description` | `DEVX-12-add-release-script` |
 | Branch commits | `<conventional commit>` | `feat: add release script` |
 | PR title | `DEVX-N: <vikunja task title>` | `DEVX-12: Add release automation` |
-| Merge commit | `DEVX-N <conventional commit>` | `DEVX-12 feat: add release script` |
+| Merge commit | `DEVX-N: <conventional commit>` | `DEVX-12: feat: add release script` |
 
 ### Task ID Resolution