feat(server): converge legacy compatibility (#15426)

#### PR Dependency Tree


* **PR #15426** 👈

This tree was auto-generated by
[Charcoal](https://github.com/danerwilliams/charcoal)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added workspace BYOK profiles with provider/model catalogs, capability
validation, connection probing, credential rotation, reordering, and
secure local leases.
* Added Copilot route options, selectable targets, managed tiers,
explicit profile/model overrides, and improved streaming with tool
callbacks and abort support.
* Added Copilot availability controls to prevent access when the feature
is disabled.
* **Changes**
* Simplified Copilot configuration and removed legacy provider-specific
settings.
* Removed obsolete model, token-cost, transcript strategy, and provider
metadata fields from public responses.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Cargo.toml

@@ -38,6 +38,7 @@ resolver = "3"
   dotenvy = "0.15"
   file-format = { version = "0.28", features = ["reader"] }
   hex = "0.4"
+  hkdf = "0.13"
   homedir = "0.3"
   image = { version = "0.25.9", default-features = false, features = [
     "bmp",
@@ -101,7 +102,7 @@ resolver = "3"
   url = { version = "2.5" }
   uuid = "1.8"
   v_htmlescape = "0.15"
-  windows = { version = "0.61", features = [
+  windows = { version = "0.62", features = [
     "Win32_Devices_FunctionDiscovery",
     "Win32_Foundation",
     "Win32_Media_Audio",
@@ -113,8 +114,9 @@ resolver = "3"
     "Win32_System_Variant",
     "Win32_UI_Shell_PropertiesSystem",
   ] }
-  windows-core = { version = "0.61" }
+  windows-core = { version = "0.62" }
   y-octo = "0.1.0"
+  zeroize = "1.9"
   zip = "8.6"
 
 [profile.dev.package.sqlx-macros]