chore: bump canton-api-client to 3.6.0-0.1.0

[scolear]

Summary

Bumps canton-api-client from 3.3.0-0.1.0 to 3.6.0-0.1.0 (regenerated from the Canton 3.6.0 OpenAPI spec).

This bump skips over 3.4.12, so the diff combines two sets of spec changes:

• 3.3.0 → 3.4.12: required fields stayed required (so e.g. interface_id/template_id are String, not Option<String>)
• 3.4.12 → 3.6.0: a number of previously required fields are now optional (booleans, identifier_filter, verbose, offset, create_argument, contract_entry, filters_by_party, …)

Changes

• crates/common/src/filters.rs — wrap now-Option<bool> fields in Some(...), use .unwrap_or_default() for interface_id/template_id to preserve the existing Option<String> local API.
• crates/ledger/src/common.rs — same adjustments; also set the new required stream_continuation_token: None field on GetActiveContractsRequest.
• crates/ledger/src/ledger_end.rs — upstream offset is now Option<i64>. Defaulting to 0 when absent to keep the existing Response.offset: i64 surface; revisit if you want to expose the optionality to callers.
• crates/ledger/src/active_contracts.rs — JsGetActiveContractsResponse.contract_entry is now Option<Box<...>>, skip entries without one; created_event.create_argument flattened from Option<Option<Value>> to Option<Value>.
• crates/examples/src/list_contracts.rs — same create_argument shape adjustment.

Notes for reviewers

• interface_id/template_id: the local InterfaceFilterValue / TemplateFilterValue still type these as Option<String> even though Canton requires them. unwrap_or_default() will produce an empty string when None, which probably doesn't match a valid filter in Canton. Consider tightening the local types to String in a follow-up.
• ledger_end.offset: defaulting None → 0 is conservative; if you want to surface a "no ledger end yet" state, change Response.offset to Option<i64> (cascades to callers).

Test plan

• cargo build succeeds for all crates in the workspace
• Integration tests against a real ledger
• Tag a new canton-lib release after merge so downstreams (cbtc-lib, dec-party-manager, dlc-attestor-stack) can pick up the new common

Closes #17