P2: ag init --force crashes with 409 instead of overwriting existing config

[OneStepAt4time]

Summary:
ag init --force should overwrite an existing .aegis config, but in current builds it can crash/return HTTP 409 (duplicate key) instead of performing the requested overwrite. This violates the documented --force behavior and causes friction for automated/CI bootstraps.

Severity: P2

Reproduction steps:

1. Ensure a config exists: ag init --yes --cwd /tmp/aegis-init-test (or create ~/.aegis/config.yaml manually).
2. Attempt a forced init: ag init --force --cwd /tmp/aegis-init-test (or ag init --yes --force as appropriate).
3. Observe: the CLI exits with an error (HTTP 409 or process crash) and the existing config is not overwritten. Check server/CLI logs.

Observed behavior:

• Running ag init --force can return a 409 conflict or crash the command instead of overwriting the config as --force implies.

Expected behavior:

• --force should replace/overwrite existing configuration files without crashing; the command should be idempotent for automation and CI usage.

What to capture for triage:

• CLI output and server logs from a run that reproduces the failure.
• The existing ~/.aegis/config.yaml (sanitise any secrets) to inspect whether a duplicate key arises from merge logic.

Notes:

• This affects automated installs and CI flows that rely on ag init --force for fresh bootstrapping. Marking P2 and assigning to @OneStepAt4time for investigation and fix.

[OneStepAt4time]

Duplicate of #3351 — same 409/crash on ag init --force. PR #3384 in progress.