fix(ui): add anyOf/oneOf support in config form (#268)

* fix(ui): add anyOf/oneOf support in config form

- Handle literal unions as dropdowns with type preservation
- Handle primitive unions (string|number, boolean|string) as text inputs
- Unwrap single-variant optional types
- Fix enum handler to preserve types via index-based values
- Update normalizeUnion to support primitive unions in schema analysis
- Exclude allOf from union normalization (stays unsupported)

Fields like Thinking Default, Allow From, Memory now render properly
instead of showing 'unsupported schema node' errors.

* UI: fix enum placeholder collision

* Docs: update changelog for PR #268

---------

Co-authored-by: Shadow <hi@shadowing.dev>

CHANGELOG.md

@@ -46,6 +46,7 @@
 - Control UI: show a reading indicator bubble while the assistant is responding.
 - Control UI: animate reading indicator dots (honors reduced-motion).
 - Control UI: stabilize chat streaming during tool runs (no flicker/vanishing text; correct run scoping).
+- Control UI: let config-form enums select empty-string values. Thanks @sreekaransrinath for PR #268.
 - Status: show runtime (docker/direct) and move shortcuts to `/help`.
 - Status: show model auth source (api-key/oauth).
 - Block streaming: avoid splitting Markdown fenced blocks and reopen fences when forced to split.