feat: add Fable model presets for Claude sessions (#860)

* feat: add Fable model presets for Claude sessions

Claude Code 2.x accepts the fable / fable[1m] model aliases for
Fable 5. hapi passes the model string through verbatim, so adding
the presets to CLAUDE_MODEL_LABELS surfaces them in the new-session
and composer model pickers, labels, and the 1M context-window
heuristic.

* test: update modelOptions full-list assertions for Fable presets

Addresses review feedback on #860: getModelOptionsForFlavor appends
every Claude preset, so the two complete-array expectations must
include the new fable entries.

shared/src/models.ts

@@ -2,7 +2,9 @@ export const CLAUDE_MODEL_LABELS = {
     sonnet: 'Sonnet',
     'sonnet[1m]': 'Sonnet 1M',
     opus: 'Opus',
-    'opus[1m]': 'Opus 1M'
+    'opus[1m]': 'Opus 1M',
+    fable: 'Fable',
+    'fable[1m]': 'Fable 1M'
 } as const
 
 export type ClaudeModelPreset = keyof typeof CLAUDE_MODEL_LABELS