Add Claude Fable 5 to the model catalog (#1443)

* Add Claude Fable 5 to the model catalog

Fable 5 (`claude-fable-5`) is the new top-tier Claude model above Opus,
but the Claude provider's model list is hardcoded in `CLAUDE_MODELS` and
was not fetched dynamically, so it never appeared in the selector.

- Add `claude-fable-5` to `CLAUDE_MODELS` (non-default; Opus 4.8 stays the
  default). Uses the Opus extended-thinking effort levels (low/medium/high/
  xhigh/max). No `[1m]` variant: Fable 5 is natively 1M context, unlike the
  Opus/Sonnet entries whose `[1m]` opts a 200K-default model into 1M.
- Teach `normalizeClaudeRuntimeModelId` the Fable family. Its version is a
  single segment (`fable-5`) rather than the `{major}-{minor}` scheme, so it
  needs its own match to map dated runtime IDs back to the catalog ID.
- Update the model-list and normalization test expectations, plus the CLI
  provider e2e catalog fixture.

Fast Mode is correctly unaffected — its allowlist is Opus 4.6/4.7/4.8 only.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* Simplify Fable runtime-ID normalization

Drop the unused `[1m]` capture from the Fable match branch. There is no
`claude-fable-5[1m]` catalog entry — Fable 5 is natively 1M context, so
there is no 200K-default model to opt into 1M — which made that path dead
code (and an untested one). Keep the `[-_ ]+` separator class for
consistency with the sibling opus/sonnet/haiku regex right below it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: lumingjun <lumingjun@bytedance.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/cli/tests/15-provider.test.ts

@@ -45,6 +45,11 @@ interface ProviderListRow {
 }
 
 const EXPECTED_CLAUDE_MODELS = [
+  {
+    id: "claude-fable-5",
+    model: "Fable 5",
+    descriptionFragment: "Most powerful",
+  },
   {
     id: "claude-opus-4-8[1m]",
     model: "Opus 4.8 1M",