feat(core): Value, reflection, codecs and results, shared by app and client

Crafter.Debug.Core is what the app side and the crafter-debug client
both need, without the session:

- Value: a JSON value with its own parser and printer, so no consumer
  interface sees a JSON library. Integers stay integers and whole
  doubles stay doubles; NaN and the infinities, which JSON cannot
  spell, are written as strings rather than hidden, because a debugger
  must not lose a NaN; invalid UTF-8 is replaced so output always
  parses. Objects keep insertion order, the order an agent reads.
- Reflect: aggregate members and names through structured-binding
  packs and source_location, taken from Crafter.DB, plus scoped-enum
  names by probing a range of values. Self-tested with static_asserts
  so a compiler that changes function_name()'s shape fails the build.
- Codec<T>: encode, decode and describe for bool, integers, floating
  point, strings, enums, optional, vector, array, string-keyed maps,
  Value, Required<T> and every aggregate. Decode reports every
  problem in a call with its path and, for a typo, the likely intended
  name, and never throws: a bad call cannot take an app down, which a
  wrongly typed parameter could in 3DForts' hand-written from_json.
- Result, Error and Async: handler results, including ones that take
  frames to arrive, so callers need no ready:false polling.

project.cpp now builds Crafter.Debug.Core as its own library, used by
both the app library and the client.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

interfaces/Crafter.Debug.cppm

@@ -1,12 +1,15 @@
 // SPDX-License-Identifier: LGPL-3.0-only
 // SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
 
-// Spike placeholder: the real API replaces this in Phase 1.
+// Runtime debugging for AI agents: what an app imports. The session, the
+// registry of commands and watches, the timeline and pause control follow in
+// later phases; for now this re-exports the shared core.
 export module Crafter.Debug;
+export import Crafter.Debug.Core;
 import std;
 
 export namespace Crafter::Debug {
     std::string_view Version() {
-        return "0.0.0-spike";
+        return "0.0.0-dev";
     }
 }