feat: Remote Connection Manager — trait-based adapters + auth + UI

[ajianaz]

Summary

Generic Connection Manager layer for CorIn — enables connecting to a remote uteke-serve (VPS) with HTTPS + auth, built once and extensible per-product via trait-based adapters.

Architecture: Trait-based Adapters (Opsi 2)

Generic Connection Layer (built once)
  ├── connections table + store (persistence)
  ├── ProductType enum + adapter traits
  ├── auth token + HTTPS on all requests
  └── Settings UI Connection tab

Product adapters (thin, per product):
  UtekeAdapter implements MemoryBackend trait
  (future: TrapFallAdapter, RunguAdapter, …)

What's new

Backend (Phases 0–3):

• connections table with full CRUD persistence
• ProductType enum + ProductAdapter / MemoryBackend traits
• UtekeAdapter wraps UtekeClient, converts types, implements traits
• UtekeClient auth: with_auth() constructor + authed() helper on every request
• Config resolution priority: DB primary → UTEKE_SERVER_URL env → TOML → default
• is_remote_url() — skips local auto-start when URL is remote
• Auto-seeds default local connection on first boot (backward compat)

Frontend (Phases 4–5):

• 6 Tauri commands: list_connections, add_connection, update_connection, delete_connection, test_connection, set_primary_connection
• ipc.ts: connection.* wrappers + ConnectionInfo + HealthInfo types
• ConnectionManager.svelte: connection cards (icon, URL, status badge), add form, test button w/ latency, set primary, delete confirm
• Settings View: new Connections section

Adding a new product (future)

// 1 line: enum variant
ProductType::TrapFall

// ~2h: implement trait
impl ProductAdapter for TrapFallAdapter { ... }

// 1 line: register
// Done — config/auth/persistence/UI is free

Files changed

File	Change
connections/mod.rs	ProductType, Capabilities, ConnectionRow/Info/Config, HealthInfo, Memory, Stats, Room, GraphNode/Edge/Response
connections/traits.rs	ProductAdapter + MemoryBackend trait definitions
connections/store.rs	Full CRUD + set_primary + get_primary + seed_default
connections/adapters/uteke.rs	UtekeAdapter wrapping UtekeClient with type conversions
uteke_client.rs	auth_token field, with_auth(), authed() on all 18 methods
config.rs	resolve_uteke_server() + is_remote_url()
lib.rs	connections table schema, commands registered, remote-aware setup
commands.rs	6 connection CRUD commands
ipc.ts	connection.* wrappers + types
ConnectionManager.svelte	Full connection management UI
SettingsView.svelte	Connections section

Closes #77 Closes #78 Closes #79 Closes #80 Closes #81 Closes #82
Related #37 (parent issue)