[AlxcBTW]

A signed-in game run asks userProfile GET /v1/users/me/blocks?limit=2000 at start, right after friends and communicationRestrictionStatus. It was not answered: the engine returned SCE_NP_WEBAPI2_ERROR_UNAVAILABLE (0x80553406) with status 0, because user_profile::answer only knew friends and profiles. A game that cannot read the block list may refuse social or multiplayer features, so this matters for every game.

• Answer GET /v1/users/{me|own account}/blocks with the blocked list of the cloud friend list the service already holds (AnyPlay accounts only, ids are account numbers). Same rules as friends: other accounts and signed-out stay not offered, offset/limit with MAX_LIMIT, same order, same Shape and override key blocks (blocks_key). No blocks gives 200 with an empty list.
• Spec spec/web-api/userProfile.md updated; tests next to the friends tests.

Checked with fmt, clippy -D warnings and the net/api tests.

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