fix: recover invalid session models and publish commit previews

[kingsword09]

Resuming a session whose saved provider, model ID, or reasoning level is no longer valid leaves the user at a prompt and fails on the next message with Model creation failed.

Inspect the decoded saved selection on both --resume and /resume and open the model picker with the specific problem. Selecting a replacement persists it through the native session API. Cancelling preserves the original selection and unsent input; an empty catalog points to provider setup. Headless prompts exit with code 1 before model creation, identify the affected model, and explain how to recover interactively. Shared defaults and conversation history are preserved.

No blanket provider remapping, lowercasing, retired-model substitution, or bulk SQLite rewrite is added. Existing upstream migrations remain in place; the recovery path handles selections that are still invalid afterward.

The reproduction uses a real persisted SQLite session and runtime with a local mock model endpoint:

bun scripts/repro-session-model.ts
bun scripts/repro-session-model.ts --case model-casing --fullscreen
bun scripts/repro-session-model.ts --case missing-model
bun scripts/repro-session-model.ts --headless

Also adds commit previews using the lockfile-pinned pkg-pr-new publisher and Bun 1.4.1. The workflow builds and tests the locked runtime, audits and install-tests the package, and publishes that exact tarball with a commit-specific executable URL.

Local validation against Desktop 3.14.0 / runtime 0.16.9: full release:build and release:pack, including TypeScript, 642 unit tests, 43 TUI component/end-to-end tests, 30 real-runtime integration tests, 5 real Node SQLite tests, runtime/PTY smoke checks, and an isolated installed-package test. Recovery coverage includes invalid providers/models/reasoning, cancellation with an unsent draft, persistence across another restart, valid selections, an empty catalog, and headless diagnostics. CI additionally validates the packaged runtime across Linux Node 22.19.0/24/26 and macOS Node 24.

Refs #160.

[pkg-pr-new]

npx https://pkg.pr.new/zcode-app-cli@9f11bce

commit: 9f11bce