[autonomy-atomicity] move-github-dotgithub exits after moving only one file

## Autonomy / Atomicity Findings

### 1. File migration helper aborts after its first move
**Category:** Ordering dependency
**File(s):** `scripts/move-github-dotgithub.sh:32-40`
**Problem:** The script runs with `set -euo pipefail`, then increments `count` with `((count++))` while `count` starts at 0. In Bash, the post-increment expression returns the old value, so the first evaluation returns status 1 and terminates the script immediately. A reproduction with two files moved the first file to `.github/`, exited with status 1, and left the second file in `github/`. This can split an agent's generated workflow changes between the two trees and prevents the optional `--push` path from completing atomically.
**Suggested fix:** Use an increment expression whose status is successful, such as `count=$((count + 1))` or `((++count))`, and add a regression test covering multiple files and the `--push` count gate.

## Suggested Actions
- [ ] Replace the post-increment at `scripts/move-github-dotgithub.sh:39` with a status-safe increment.
- [ ] Add a test or shell-level validation proving all source files move before the script exits.

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[What is this?](https://ela.st/github-ai-tools) | [From workflow: Trigger Autonomy Atomicity Analyzer](https://github.com/elastic/ai-github-actions/actions/runs/29760050275)

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Start with scripts/move-github-dotgithub.sh:32-40 and reproduce the failure using multiple files in the source directory. Replace the status-sensitive increment and add a shell-level regression check showing that all files move before exit, including the optional --push count gate.

Written by the indexing model from the issue text.