fix(mcp): honest inbound annotations + wording, aligned with the hosted app

[tuyakhov]

Summary

The 0.14.0 manifest ships the inbound tool suite with annotations/wording the app had already deliberately corrected app-side (senderkit-app lib/mcp/tools.ts APP_ONLY_TOOLS, see app PRs #283/#285). This aligns the manifest with the app so a follow-up app PR can collapse the app-side inbound definitions onto the manifest (wire inbound handlers into HANDLERS and delete the duplicated ToolDefs). Same adoption pattern as #92 (cc/bcc/limit wording).

• senderkit_inbound_addresses_create → destructiveHint: false: an additive create that deleting the address fully reverses; destructiveHint: true made well-behaved clients demand confirmation for a reversible operation.
• livemode no longer promises a quota exemption: the manifest claimed test-mode addresses "don't count against quota", but the plan limit applies to every address. Now uses the honest wording (the app's tests forbid the quota-exemption promise).
• Titles: inbound_messages_list / inbound_messages_get retitled "List Inbound Messages" / "Get Inbound Message" to match the app's served titles.
• All remaining inbound descriptions + field descriptions aligned with the app, including the friendly ISO 8601 validation message on the before cursor.

Second commit — accuracy over blind parity. Where neither copy matched the actual implementation, both sides were corrected together instead of copying an incomplete description (app counterpart: senderkit-app#287, identical strings, byte-parity preserved — verified against the built dist):

• localPart documents the "*" catch-all and the charset rules (both real: normalizeLocalPart accepts "*" and enforces 1-64 chars of a-z 0-9 . _ -, lowercased, reserved names rejected).
• webhookEndpointId documents both halves of endpoint selection: a bound endpoint receives message.received even when not subscribed; unbound addresses fan out to every active subscribed endpoint in the address's mode.
• livemode notes that a test-mode address's forwards are recorded as test sends without real delivery.

Tests

• mcp.test.ts: parity block pinning the corrected annotation, the no-quota-promise wording (mirrors the app's test), the adopted titles, the ISO 8601 before message, plus wording guards for the catch-all/charset docs, the unbound fan-out, and the test-mode forward note — each written first and watched fail.
• CLI mcp-server.test.ts expectations extended to support a destructiveHint: false write.
• Full workspace green: build, typecheck, sdk 86/86, cli 87/87, react-email 29/29.

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