feat: add USER.md and TOOLS.md to bootstrap framework

Introduce user profile (USER.md) and machine tool reference (TOOLS.md)
as first-class framework files. Both ship as generic defaults and are
personalized via mosaic init.

- Add USER.md/TOOLS.md defaults and parameterized templates
- Update AGENTS.md load order (6 → 8 steps)
- Update SOUL.md: default name "Assistant", add trash/mental-notes guardrails
- Update install.sh: preserve USER.md/TOOLS.md on reinstall
- Update mosaic-init: interactive USER.md + TOOLS.md generation
- Update mosaic-doctor: existence checks for new files
- Update mosaic launcher: inject USER.md/TOOLS.md into runtime prompt
- Update README: architecture diagram, generic-repo policy note

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bin/mosaic

@@ -148,6 +148,17 @@ For required push/merge/issue-close/release actions, execute without routine con
 EOF
 
   cat "$MOSAIC_HOME/AGENTS.md"
+
+  if [[ -f "$MOSAIC_HOME/USER.md" ]]; then
+    printf '\n\n# User Profile\n\n'
+    cat "$MOSAIC_HOME/USER.md"
+  fi
+
+  if [[ -f "$MOSAIC_HOME/TOOLS.md" ]]; then
+    printf '\n\n# Machine Tools\n\n'
+    cat "$MOSAIC_HOME/TOOLS.md"
+  fi
+
   printf '\n\n# Runtime-Specific Contract\n\n'
   cat "$runtime_file"
 }