feat: mr-reviewer and solution-reviewer join the scaffold, so they exist in a repo

Eleven agents lived only in `~/.claude/agents/`, which is not a git repository —
they would have gone with the laptop. Eight of those were product-specific
reviewers already defined in the projects that need them, and they are removed from
the user level rather than duplicated here. Two were genuinely generic and already
product-neutral (zero references to any product, customer or employer), so they
belong in the shared scaffold: `mr-reviewer` reviews open MRs/PRs on a non-primary
remote in a multi-remote repository, and `solution-reviewer` does a whole-codebase
health review.

`irs-validator` is deliberately NOT brought in. It is personal tooling rather than
a development capability, and per the user CLAUDE.md personal tooling must not be
referenced inside a project repository because those are mirrored to other remotes.

The client manifest gains `fetch` and `websearch` capability mappings, which
`solution-reviewer` needs. Worth noting how that surfaced: the sync REFUSED to
render rather than dropping the two tools silently, which is the fail-safe
behaviour the capability mapping exists to provide — an unmapped capability that
rendered as absent would have quietly removed the agent's web access.

`~/.claude/agents/README.md` now records that ten of the eleven agents there are
installed output from this repository, how to regenerate and reinstall them, and
which one is deliberately personal.

.agents/clients/claude-code.yaml

@@ -20,6 +20,8 @@
     "search": "Grep",
     "list": "Glob",
     "shell": "Bash",
-    "write": "Write"
+    "write": "Write",
+    "fetch": "WebFetch",
+    "websearch": "WebSearch"
   }
 }