merge: origin/main into next for the 0.0.50 integration line

next carries 108 commits main lacks; main carries 23 next lacks, including
the MOSAIC_GIT_IDENTITY work that per-agent git credentials depend on.
Neither stream alone can ship 0.0.50: next drops identity, main drops
everything since the split.

Conflicts and how they were settled:
- packages/mosaic/package.json test:framework-shell -- union. Neither side
  removed an entry; next added 6, main added 8, one shared. 50 total.
- framework/tools/git/pr-merge.sh -- next's form. It permits base 'main' or
  'next'; main's permits 'main' only, and the release line targets next.
- framework/tools/git/test-ci-queue-wait-tristate.sh -- both sides appended
  to the same region (next: merge-readiness assertions; main: a real-clock
  watchdog control). Kept both.
- docs/SITEMAP.md -- both sides appended distinct sections. Kept both.

packages/mosaic/framework/runtime/claude/settings.json

@@ -64,6 +64,16 @@
             "timeout": 10
           }
         ]
+      },
+      {
+        "matcher": "Bash",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "~/.config/mosaic/tools/git/wrapper-guard.sh",
+            "timeout": 10
+          }
+        ]
       }
     ],
     "PostToolUse": [