feat(svelte): update reactive client lifecycle and diagnostics

[brittianwarner]

• Update the Svelte client introduced in feat(frontend): add svelte #4532 for public RivetKit 2.3.17 and Svelte 5.57, preserving the existing context helpers and deprecated preload alias.
• Improve reactive subscription ownership, remount/reconnect behavior, dynamic connection parameters, action deadlines, shared connections, and warm-up/preconnect helpers.
• Add opt-in connection diagnostics with opaque identifiers, structured error helpers, and regression coverage for remount cleanup and credential redaction.
• Keep the package framework-only with generic examples, public dependencies, and distributable exports; document that adapter timeouts do not cancel server execution or the SDK's WebSocket action waiter.
• Validate 119 tests, zero-error/zero-warning type checking, package build, and a packed standalone consumer's browser build, SSR build, and SSR render against unmodified public dependencies.

[the-company-company]

✅ No issues found

_{Reviewed commit ef1ea99.}