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/src/types.ts

@@ -25,7 +25,7 @@ export type CodeJsonValue = null | boolean | number | string | CodeJsonValue[] |
  * injects a real error constructor under `name`; rejected member calls become
  * its instances and expose the exact member name through
  * `memberNameProperty`. Both strings are runtime data rather than knowledge
- * of a particular consumer such as Code Mode.
+ * of a particular consumer such as PTC mode.
  */
 export interface CodeBindingErrorClass {
   /** Constructor global and resulting `Error.name`; same portable identifier rule as {@link CodeBindingNamespace.global}. */