ODIAN Launcher: hub, installer, local stack and remembered sign-in (M2)

- Tauri 2 + Svelte 5 hub in ODIAN dark: patch notes and roadmap, install and
  update progress, local stack status, settings with DHP and MCP addresses.
- crates/odian-packs: Rust installer for pack format v1 (signed manifests,
  resumable verified downloads from a DHP or an ODIAN drive), byte-compatible
  with ODIAN_MCP_Server's Python odian_packs.
- Local stack on 127.0.0.1: Postgres -> Engine API -> tile server -> Odian.exe,
  one Job Object, clean shutdown; database snapshot restore on a fresh PC only.
- Keycloak sign-in through the DHP's MCP, remembered until Sign out with a
  launcher session that renews the Engine token silently.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Cargo.toml

@@ -0,0 +1,10 @@
+[workspace]
+resolver = "2"
+members = ["src-tauri", "crates/odian-packs"]
+
+[profile.release]
+# The launcher downloads and hashes hundreds of GB; keep the hot paths optimised
+# while the binary stays small.
+lto = "thin"
+codegen-units = 1
+strip = true