fix(server): improve self hosted usability (#15510)

fix #15505
fix #15502
fix #15496
fix #15491

#### PR Dependency Tree


* **PR #15510** 👈

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 configurable delays for invitations, invite links, and document
publishing by newly created accounts.
- Added workspace action checks that explain blocked actions and retry
timing.
- BYOK setup now verifies model capabilities and saves only validated
options.

- **Bug Fixes**
- Improved BYOK probing for chat, structured responses, tool calls,
embeddings, reranking, and image generation.
  - Preserved probe request order and strengthened response validation.
  - Authentication configuration changes now reload correctly.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Cargo.lock

@@ -4758,9 +4758,9 @@ dependencies = [
 
 [[package]]
 name = "llm_adapter"
-version = "0.2.20"
+version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5d13be366ea35d2a9966ad5770e3d070e495af4e1e6dd009638dee4b55ab45ed"
+checksum = "02c6b4fa5178b8183331a7d51e8f7ece5421ecb966d3431f3d9ce3c724c6fcc0"
 dependencies = [
  "base64",
  "jsonschema",