rename code-mode to ptc (PTC mode), except session-persistent vocabulary

Rename the tool-presentation transport from code-mode to ptc everywhere
that is not written into session logs: the mode config value becomes 'ptc',
the preset directory/id becomes ptc, the demo becomes demo:ptc, the
dispatch waterfall becomes tools/ptc-dispatch-log (types PtcDispatch*), the
prompt rule becomes tools:ptc-only, source/test files become ptc.ts etc.,
and prose says PTC mode / PTC 模式. The session-persistent vocabulary
(durable events tool/code-dispatch*, logged plugin name tools-code-mode,
sub-call id segment :code:) intentionally stays and moves in the stacked
persistence PR, which is blocked until the SESSION_FORMAT_VERSION v0→v1
migration lands with it. run_code, its code parameter, CodeSdkLanguage,
CodeRunFailedError, the dsh-code-runtime family, third-party codex names,
and frozen archived notes keep their names.

packages/code-runtime/code-runtime-worker-thread/tests/bootstrap.spec.ts

@@ -62,7 +62,7 @@ async function rejectionOf(promise: Promise<unknown>): Promise<unknown> {
 const BOOT = { maxOutputBytes: 65_536 }
 const TOOL_ERROR_CLASS = { name: 'ToolCallError', memberNameProperty: 'toolName' } as const
 
-/** One worker declaration for the Code Mode tools namespace. */
+/** One worker declaration for the PTC mode tools namespace. */
 function toolNamespace(names: string[]) {
   return { global: 'tools', names, errorClass: TOOL_ERROR_CLASS }
 }