feat(#1434): registry-driven dispatch for third-party capabilities (ADR-1244 Phase 5) (#1450)

ADR-1244 Phase 5 (D7). dispatchOverlayCapabilityCommand in gsd-tools.cjs dispatches an installed third-party capability command family via loadRegistry({includeInstalled}), gated on a committed ledger entry (consent) and confined to the capability's install root (defaultRequireFromInstallRoot: bare-.cjs basename + realpath containment, rejects ../ traversal + symlink escape); same own-property/function/sync/ExitError guards as the first-party path. capability-loader records _overlay.commandRoots only for accepted overlay caps with a committed, structurally-valid ledger entry (fail closed). First-party graphify/intel/audit unchanged (already on the registry seam). 3 Codex rounds converged + /security-review (no HIGH) + /code-review (Approve); gsd-test green both platforms; CI green.

Closes #1434.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.changeset/plucky-tigers-dart.md

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+---
+type: Added
+pr: 1450
+---
+**Third-party capabilities can ship dispatchable CLI commands (ADR-1244 Phase 5)** — a capability that declares a `commands` family is now dispatched by `gsd-tools <family>` via the registry, the same seam the first-party `graphify`/`intel`/`audit` commands already use. Third-party command dispatch runs only for an installed, consented capability (a committed ledger entry) and loads the router module strictly from that capability's own install root (basename + realpath confinement, rejecting `..` traversal and symlink escape); a bundle merely present on disk with no install record keeps its declarative surfaces but is never command-dispatchable. (#1450)