Support all six document attachment targets in document create/update/list/view

[schpetbot]

Linear attaches every document to exactly one target — project, issue, initiative, team, cycle, or release — and documentCreate now rejects targetless documents outright. The CLI only exposed --project/--issue on create, --project on update, and slug-only --project plus --issue on list.

This goes beyond the literal report (create flags) to make attachment support consistent everywhere, per the six-target model:

• Shared attachment-target module backing create, update, and list: six long-only flags, client-side exactly-one validation before any network/editor/stdin work (errors name CLI flags, not GraphQL fields), and --team + --cycle collapsing into one team-scoped cycle target, matching the issue commands.
• create gains --initiative, --team, --cycle, --release; the interactive "Nothing (workspace document)" option is removed (it always fails server-side now) and the prompt offers all six targets.
• update gains all target flags including the previously missing --issue; a target flag re-points the document (the server clears the old target).
• list gains the same filters, resolved to relation IDs — this also fixes --project silently matching slug IDs only, and makes invalid filter input error instead of returning an empty list. The ATTACHMENT column now labels the target type (Team: Linear CLI (CLI), Cycle: CLI #2 — Polish sprint, …).
• view selects and renders all six associations; --json output keeps GraphQL field names/nesting.
• New shared resolvers: resolveInitiativeId (UUID/slug/name) and resolveReleaseId (UUID/name/version, paginated to exhaustion) — both reject ambiguous matches with a candidate listing instead of picking one silently.
• First commit is a sync-schema refresh: the vendored schema predated releaseId/cycleId on the document inputs, ReleaseFilter, and Document.cycle/Document.release.

Notes:

• teamId/initiativeId/cycleId are marked [Internal] in Linear's schema but verified working with a regular API key (as issueId was before it became public); failures would surface cleanly through the existing error handling.
• Live-QA'd against a real workspace for project/issue/team/cycle/initiative targets including re-pointing. Release attachment is covered by mocked tests and the refreshed schema only — releases require a Business plan, which the QA workspace doesn't have.

Fixes #260