workflow: meta rides the seam as data — the engine never evaluates it

P1 review finding: extractMeta timed only the literal's vm evaluation;
materializing the RESULT then read properties ordinarily on the HOST
stack, so a meta literal smuggling a getter (get name() { while(true){} })
could wedge the host outside any timeout — defeating the exact spin
isolation the worker thread exists for.

Rather than harden the evaluator (descriptor walks, AST validation),
delete the mechanism: the workflow's identity now reaches the seam as a
plain JSON field (WorkflowStartRequest.meta), carried by the tool as a
schema-validated `meta` object parameter the model fills directly. The
engine only shape-validates data (validateMeta, every violation named)
and pre-parses the body; the scanner, the vm evaluation, and the
host-side materialization are gone, and with them the hole. A body
still opening with a Claude Code-style `export const meta` statement
gets a pointed SCRIPT_PARSE message (the likeliest authoring slip; a
CC script's body stays drop-in, only its meta header moves into the
parameter). syncTimeoutMs now governs exactly one thing: the initial
synchronous slice inside the worker.

The RFC's decision section is rewritten in place (implemented-RFC
rule); the embedded-meta format moves to alternatives-considered with
the hole as the reason. Tool description, presentation (title now reads
meta.name directly — the textual sniff is gone), seam vocabulary docs,
and catalogs follow.

docs/config-catalog.md

@@ -685,7 +685,7 @@ export interface Config {
 }
 ```
 
-Source: [`packages/workflow/tool-workflow/src/index.ts:40`](../packages/workflow/tool-workflow/src/index.ts)
+Source: [`packages/workflow/tool-workflow/src/index.ts:39`](../packages/workflow/tool-workflow/src/index.ts)
 
 ## `@deepseek-ai/dsh-web`
 
@@ -815,7 +815,7 @@ export interface Config {
   maxTotalAgents?: number
   /** Items accepted by a single `parallel()`/`pipeline()` call (default 4096). */
   maxItemsPerCall?: number
-  /** vm timeout for the initial synchronous slice (inside the worker) AND the host-side meta evaluation (default 5000 ms). */
+  /** vm timeout for the script's initial synchronous slice, inside the worker (default 5000 ms). */
   syncTimeoutMs?: number
   /**
    * How long after a cancellation an unsettled script may keep running before