feat(series): conditional early termination and custom completion message

[joshunrau]

Summary

Adds conditional early-termination support to SERIES instruments, along with the supporting renderer, gateway, and API changes needed to make it work end-to-end (in-person and remote assignments).

Series feature

• terminate predicate (params.terminate): called after each item is submitted; returning true ends the series early so the remaining items are never administered. The terminating item's own record is still saved. Example use: a consent form as the first item that, when declined, skips the rest.
• completionMessage (params.completionMessage): returns a custom localized ({ en, fr }) message for the completion screen, or null for the default. Receives { terminated, itemName } so the message can differ on early exit (e.g. "the questionnaire was not administered because you did not consent").
• Typed authoring via generics: defineSeriesInstrument now infers the item-name literal union, so terminate/completionMessage receive a strongly-typed itemName. Item data is a generic defaulting to any, so it can be annotated inline without a cast.

Renderer / gateway

• SeriesInstrumentRenderer evaluates terminate, jumps to the completion screen on early exit, renders the custom completionMessage, and emits a new complete flag on the submit payload.
• Gateway (Root.tsx) marks a remote assignment COMPLETE via the complete flag instead of comparing against the last item's id, so early termination completes the assignment correctly.

API synchronizer (gateway.synchronizer.ts)

• Fix: a completed series may now contain fewer records than items (an early-terminated prefix); previously the sync threw on a strict length mismatch. Validation now accepts a non-empty prefix and checks cipher-text/symmetric-key counts against each other.
• Better error logging: per-step failure logs (decrypt / parse / create) that identify the failing instrument and include the relevant payload, replacing an unreadable dump of the whole assignment (which also leaked the private key and large base64 blobs).

Consent form

• DNP_GENERAL_CONSENT_FORM: changed the consent field from a checkbox to an accept/decline radio, and relaxed its schema from z.literal(true) to z.boolean() so a decline is submittable (which drives the new early-exit demo in DNP_HAPPINESS_QUESTIONNAIRE_WITH_CONSENT).

Docs / tests

• Documented terminate and completionMessage in packages/instrument-guidelines/AGENTS.md.
• Added schema tests for the new params (instrument.series.test.ts).
• Added CLAUDE.md.

Verification

• pnpm lint and pnpm test pass (36 test files, 244 passed / 1 pre-existing skip).

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