feat: integrate framework files into monorepo under packages/mosaic/framework/

Moves all Mosaic framework runtime files from the separate bootstrap repo
into the monorepo as canonical source. The @mosaic/mosaic npm package now
ships the complete framework — bin scripts, runtime configs, tools, and
templates — enabling standalone installation via npm install.

Structure:
  packages/mosaic/framework/
  ├── bin/          28 CLI scripts (mosaic, mosaic-doctor, mosaic-sync-skills, etc.)
  ├── runtime/      Runtime adapters (claude, codex, opencode, pi, mcp)
  ├── tools/        Shell tooling (git, prdy, orchestrator, quality, etc.)
  ├── templates/    Agent and repo templates
  ├── defaults/     Default identity files (AGENTS.md, STANDARDS.md, SOUL.md, etc.)
  ├── install.sh    Legacy bash installer
  └── remote-install.sh  One-liner remote installer

Key files with Pi support and recent fixes:
- bin/mosaic: launch_pi() with skills-local loop
- bin/mosaic-doctor: --fix auto-wiring for all 4 harnesses
- bin/mosaic-sync-skills: Pi as 4th link target, symlink-aware find
- bin/mosaic-link-runtime-assets: Pi settings.json patching
- bin/mosaic-migrate-local-skills: Pi skill roots, symlink find
- runtime/pi/RUNTIME.md + mosaic-extension.ts

Package ships 251 framework files in the npm tarball (278KB compressed).

packages/mosaic/framework/tools/excalidraw/loader.mjs

@@ -0,0 +1,76 @@
+/**
+ * Custom ESM loader to fix missing .js extensions in @excalidraw/excalidraw deps.
+ *
+ * Problems patched:
+ * 1. excalidraw imports 'roughjs/bin/rough' (and other roughjs/* paths) without .js
+ * 2. roughjs/* files import sibling modules as './canvas' (relative, no .js)
+ * 3. JSON files need { type: 'json' } import attribute in Node.js v22+
+ *
+ * Usage: node --loader ./loader.mjs server.mjs [args...]
+ */
+
+import { fileURLToPath, pathToFileURL } from 'url';
+import { dirname, resolve as pathResolve } from 'path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+
+// Modules that have incompatible ESM format — redirect to local stubs
+const STUBS = {
+  '@excalidraw/laser-pointer': pathToFileURL(pathResolve(__dirname, 'stubs/laser-pointer.mjs')).href,
+};
+
+export async function resolve(specifier, context, nextResolve) {
+  // 0. Module stubs (incompatible ESM format packages)
+  if (STUBS[specifier]) {
+    return { url: STUBS[specifier], shortCircuit: true };
+  }
+
+  // 1. Bare roughjs/* specifiers without .js extension
+  if (/^roughjs\/bin\/[a-z-]+$/.test(specifier)) {
+    return nextResolve(`${specifier}.js`, context);
+  }
+
+  // 2. Relative imports without extension (e.g. './canvas' from roughjs/bin/rough.js)
+  //    These come in as relative paths that resolve to extensionless file URLs.
+  if (specifier.startsWith('./') || specifier.startsWith('../')) {
+    // Try resolving first; if it fails with a missing-extension error, add .js
+    try {
+      return await nextResolve(specifier, context);
+    } catch (err) {
+      if (err.code === 'ERR_MODULE_NOT_FOUND') {
+        // Try appending .js
+        try {
+          return await nextResolve(`${specifier}.js`, context);
+        } catch {
+          // Fall through to original error
+        }
+      }
+      throw err;
+    }
+  }
+
+  // 3. JSON imports need type: 'json' attribute
+  if (specifier.endsWith('.json')) {
+    const resolved = await nextResolve(specifier, context);
+    if (!resolved.importAttributes?.type) {
+      return {
+        ...resolved,
+        importAttributes: { ...resolved.importAttributes, type: 'json' },
+      };
+    }
+    return resolved;
+  }
+
+  return nextResolve(specifier, context);
+}
+
+export async function load(url, context, nextLoad) {
+  // Ensure JSON files are loaded with json format
+  if (url.endsWith('.json')) {
+    return nextLoad(url, {
+      ...context,
+      importAttributes: { ...context.importAttributes, type: 'json' },
+    });
+  }
+  return nextLoad(url, context);
+}