chore(cli): bump @fern-api/generator-cli to 0.9.50

[devin-ai-integration]

Description

Follow-up to #17083. Now that @fern-api/generator-cli@0.9.50 (which pulls in @fern-api/replay@0.19.1) is published to npm, this advances the catalog pin so the Fern CLI and generators pick it up.

Changes Made

• pnpm-workspace.yaml: @fern-api/generator-cli catalog 0.9.49 → 0.9.50
• pnpm-lock.yaml: regenerated (resolves generator-cli 0.9.50 → replay 0.19.1)
• Added CLI changelog entry packages/cli/cli/changes/unreleased/bump-generator-cli-0-9-50.yml (fix)
• Updated README.md generator (if applicable) — n/a

Testing

• pnpm install --lockfile-only resolves generator-cli 0.9.50 → replay 0.19.1
• Unit tests added/updated — n/a (dependency pin bump)

Link to Devin session: https://app.devin.ai/sessions/425e5bcb78b8433cbd606d8e2e3ce48f
Requested by: @tstanmay13

[devin-ai-integration]

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[nitpickybot]

Routine dependency pin bump of @fern-api/generator-cli from 0.9.49 to 0.9.50. Workspace catalog, lockfile, and changelog entry are consistent. No issues found.