[BUG][bedrock] /model picker's Haiku 4.5 quick-pick writes bare alias "claude-haiku-4-5" -> 400 invalid model identifier

### Preflight checklist

- [x] I searched existing issues and this hasn't been reported yet
- [x] This is a single bug report
- [x] I am using the latest version of Claude Code

### What's wrong

On a Bedrock-backed setup (`CLAUDE_CODE_USE_BEDROCK=1`), selecting "Haiku 4.5" from the `/model` picker fails every request with:

```
API Error (claude-haiku-4-5): 400 The provided model identifier is invalid.
```

The picker persists the bare catalog alias `claude-haiku-4-5` instead of resolving it to the region-prefixed, dated Bedrock inference-profile ID. Note this is missing both the region prefix (`eu.anthropic.` / `us.anthropic.`) and the date suffix (`-20251001-v1:0`) - worse than the Opus 4.8 case in #68005, which is only missing the region prefix.

Every other Haiku-selection path in the same setup works correctly, because each of them already uses the full ID:

- `settings.json` top-level `"model": "eu.anthropic.claude-haiku-4-5-20251001-v1:0"` - works
- `CLAUDE_CODE_SUBAGENT_MODEL=eu.anthropic.claude-haiku-4-5-20251001-v1:0` - works
- Agent tool `model: "haiku"` shorthand for subagents - works (resolves correctly there)

So this looks isolated to the interactive `/model` picker's built-in "Haiku 4.5" quick-pick entry for the main session model specifically.

### What should happen

`/model` should persist the Bedrock-qualified model ID when the active provider is Bedrock, same as every other selection path already does.

### Workaround

Type the full ID directly instead of using the picker's quick-pick row:

```
/model eu.anthropic.claude-haiku-4-5-20251001-v1:0
```

### Prior art

This looks like the same underlying bug class as #68005 (Opus 4.8 `[1m]`, missing region prefix only) and the earlier Opus 4.6/4.7 regressions referenced there (#23499 closed, #61495 open). Each new model release seems to re-introduce this because the picker's ID resolution doesn't account for the Bedrock prefix/date-suffix requirements. Filing separately since it's the Haiku 4.5 entry and the failure mode is slightly different (missing both prefix and suffix, not just prefix).

### Error messages/logs

```
API Error (claude-haiku-4-5): 400 The provided model identifier is invalid.
```

### Claude model

Haiku 4.5

### Is this a regression

Unclear - haven't confirmed a prior working version for this specific picker entry.

### Claude Code version

2.1.209

### Platform

AWS Bedrock

### Operating system

macOS

Start at the interactive /model picker and compare its Haiku 4.5 quick-pick resolution with the working settings.json, CLAUDE_CODE_SUBAGENT_MODEL, and Agent tool shorthand paths. Done means selecting Haiku 4.5 on Bedrock persists and uses the full region-prefixed, dated inference-profile ID rather than the bare alias.

Scritto dal modello di indicizzazione a partire dal testo della issue.