F14.1d — Persist durable guided-session project state

[Flow-Fly]

Parent: #129. Depends on the serializable guide output from the generator children.

Scope

Add optional durable guided-session state to each ProjectContext and to the full-fidelity .pf project schema.

Implementation

• Add an optional guided-session file type containing target dimensions, target indices, generation settings, and creation metadata.
• Bump PROJECT_VERSION according to the repository schema rule.
• Add project-local guided state; do not use a global singleton for project-owned data.
• Save and load the optional payload through ProjectStore.
• Keep older and ordinary projects valid when the payload is absent.
• Provide an explicit clear operation for the later Finish guidance flow.

Acceptance

• Save/load round-trips preserve all guide bytes and generation settings.
• Two simultaneous project contexts keep independent guided sessions.
• Missing guided data loads as inactive without migration errors.
• Clearing guided state changes no layer, frame, cel, palette, or history data.

Verification

• Schema and two-context Vitest coverage
• npm run lint
• npm run build
• git diff --check

[Flow-Fly]

Completed in PR #310. The implementation is merged into develop at b3bf845 and the post-merge CI run 29084411483 passed.