docs(tools): align Code Mode docs with multi-language dispatch; py-types notes

Address ds-review-bot v5/v6 review round 3:
- Config.mode JSDoc and the regenerated config-catalog no longer claim Code
  Mode requires a TypeScript runtime; both now say a language with a
  registered SDK renderer.
- The active 2026-06-15-code-mode base note (both languages) follows shipped
  reality: the SDK renders the loaded runtime's language, dsh-tools accepts
  any language with a renderer and run_code flavor, and it cross-links the
  language-dispatch note.
- The language-dispatch note distinguishes the two Object.hasOwn guards'
  reachability and documents the peekRuntime no-runtime degrade vs the
  rejected silent fallback.
- SDK_RENDERERS comment: adding a language is two table entries, not one.
- py-types: document the deliberate PEP 586 deviation for float Literals;
  add oneOf-object-branch tests (named union classes and context-free
  degrade), keeping py-types.ts at 100% per-file coverage.

docs/config-catalog.md

@@ -2021,8 +2021,9 @@ export interface Config {
   /**
    * Model presentation. `native` (default) sends every visible schema; `code`
    * sends only `run_code` plus a generated SDK prompt; `both` sends both forms.
-   * Code modes require a TypeScript runtime and fail prompt assembly when it is
-   * absent or mismatched. Under `code`, native names in `toolOrder` are invalid.
+   * Code modes require a `ctx.codeRuntime` whose `language` has a registered
+   * SDK renderer (TypeScript or Python) and fail prompt assembly when it is
+   * absent or has no renderer. Under `code`, native names in `toolOrder` are invalid.
    */
   mode?: ToolPresentationMode
   /**
@@ -2039,7 +2040,7 @@ export interface Config {
 export type ToolPresentationMode = 'native' | 'code' | 'both'
 ```
 
-Source: [`packages/core/tools/src/index.ts:603`](../packages/core/tools/src/index.ts)
+Source: [`packages/core/tools/src/index.ts:605`](../packages/core/tools/src/index.ts)
 
 ## `@deepseek-ai/dsh-tui`