Sense: add commercial platform adapter contracts

[oratis]

What

• add fail-closed adapter profiles for Threads, Instagram, LinkedIn, X, TikTok, YouTube, and Facebook Pages
• codify account types, OAuth scopes, platform/app review gates, version policies, pricing notices, and media delivery requirements
• validate platform-specific required fields and conservative limits
• model each official multi-step publish/upload/status protocol without storing credentials or claiming production readiness
• add lisa sense social readiness and an implementation/external-gates record to the main design doc

Why

Commercial platforms require app ownership, product review, paid quota, business verification, public media staging, or compliance audits that cannot be completed inside this repository. This contract layer makes those dependencies executable and prevents an unreviewed connector from appearing ready.

Impact

Bluesky/Mastodon remain the live rollout. The seven commercial adapters stay draft-only (or private-test-only for unaudited TikTok/YouTube) until a platform app owner provides credentials and passes the recorded external gates. This PR is stacked on #326.

Checks

• npm run typecheck
• npm test (1471 passed, 1 skipped)
• commercial adapter contract tests for all seven platforms
• partial-publication failure injection
• git diff --check