Leave the explicit type key to the collection in starter types

[callumalpass]

Apps create records by naming a type (create({ type: "person", … })), and the engine records it under the collection's configured settings.explicit_type_keys: type by default, but e.g. mdbase_type in Reader collections where type holds CSL data. Three starters also required type and pinned it to their own name, so their records fail validation in any collection whose key is something else:

explicit_type_keys: [mdbase_type]  →  create person  →  schema_required: type

View's closed top-level schema (additionalProperties: false) additionally rejected whichever key it did not declare, so no View type file could work under both keys.

Changes

• types/person/3.md, types/comment/2.md, types/view/2.md: drop the pinned type property and its required entry. View v2's top level accepts unknown fields (nested query-language objects stay strict). Each keeps match: where: type: <name> so hand-written type: <name> records are still recognised, including in collections without explicit keys.
• mdbase.contact 1.3.0, mdbase.comment 1.0.1, mdbase.view 1.0.1 ship them with upgrade_from the previous starter, so an unmodified installed seed is offered a reviewed upgrade. The superseded packs are visibility: hidden; their provisions stay byte-identical to main (contact 1.2.0 is now asserted alongside 1.0.0/1.1.0).
• scripts/starter-type-keys.test.mjs: every current starter leaves type/types undeclared and unrequired and is not closed at the top level.
• Comment tests read the v2 starter; a comment without type, or with mdbase_type, is valid. The People install matrix adds 1.3.0 and 1.2.0 → 1.3.0.

Behaviour (mdbase CLI, person starter)

explicit_type_keys	app-created, before → after	hand-written type: person
[type, types]	valid → valid	valid
[mdbase_type]	invalid → valid	valid (via match)
[]	invalid → invalid (no key to record membership)	valid

Not in this PR

• runtime_* types are synced from the spec's standard packs, are closed, and their contracts map a contract field to type; that needs a contract-level decision.
• contact v2 is no longer installed by any offered pack.
• Downstream copies (Reader, Writer, Editor, TaskNotes) need their vendored packs updated after this merges.

Verification

npm test with MDBASE_VERIFY_CLI (mdbase 0.1.0-beta.120): 27 unit tests and 42 pack tests pass, including CLI dry run, install and repeat assessment of every catalog pack.