fix(sync): do not blank a ResourceTarget id when the lookup misses

[cplieger]

Managed-mode writeback can emit TOML that Komodo itself cannot parse, which leaves the sync broken until someone edits the file by hand. Hit this on a live deployment; the deploy pipeline stopped until I removed the offending line.

What happens

A Commit Sync wrote this into resources.toml:

[[alerter]]
name = "Discord-stack-state"
[alerter.config]
alert_types = ["StackStateChange"]
resources = [{ type = "Stack" }]

Every read after that failed:

ERROR: failed to read resources from ".../resources.toml"
  1: failed to parse resource file contents
  2: TOML parse error at line 1548, column 14
     resources = [{ type = "Stack" }]
                  ^^^^^^^^^^^^^^^^^^
     missing field `id`

Why

1. replace_resource_target_ids! rewrote each id to the resource name with .map(|r| r.name.clone()).unwrap_or_default(), so a missed lookup yields an empty String.
2. ResourceTarget is adjacently tagged, #[serde(tag = "type", content = "id")], so id is required to deserialize.
3. TOML_PRETTY_OPTIONS sets skip_empty_string: true, so the empty id is omitted from the emitted table.

In my case the lookup missed because the file supplied the target by name, which is how every other synced reference is written, while the cache is keyed by id. Whether names should be accepted in that position is a separate question; this PR only stops a miss from corrupting the file.

The change

Leave the id untouched when the lookup misses. On a hit nothing changes; on a miss the previous outcome was a file that cannot be read back.

DeploymentImage::Build has the same shape (build_id blanked, adjacently tagged) and is covered in #1584. The plain String fields nearby (server_id, swarm_id, linked_repo, builder_id) still parse when empty, so they are unaffected.

Verification

cargo check -p komodo_core clean with no new warnings, cargo fmt --check clean. No test: the macro reads the global all_resources_cache() and bin/core has no test scaffolding for it.