fix(integrations): declare OmpIntegration multi_install_safe (#3650)

* fix(integrations): declare OmpIntegration multi_install_safe

OmpIntegration is a plain MarkdownIntegration whose files live only under
its isolated, static root .omp/commands/, disjoint from every other
integration. But it never declared multi_install_safe, so it inherited the
IntegrationBase default False — leaving `specify integration status` in a
permanent unsafe-multi-install ERROR state whenever omp is co-installed
alongside another agent, with no acknowledgment path.

Add `multi_install_safe = True`, mirroring the isolated MarkdownIntegration
cohort (qwen, shai, qodercli, junie, kilocode) and the kiro-cli #3471 fix.
The parametrized registry isolation contracts auto-include omp once the flag
is set and pass (.omp/commands is isolated and its manifest disjoint).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* docs(integrations): list omp in the multi-install-safe reference table

Declaring OmpIntegration multi_install_safe means the reference table in
docs/reference/integrations.md (which states it lists all currently
declared multi-install-safe integrations) should include it. Add the
alphabetized omp row with its .omp/commands isolation path.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/specify_cli/integrations/omp/__init__.py

@@ -20,6 +20,7 @@ class OmpIntegration(MarkdownIntegration):
         "args": "$ARGUMENTS",
         "extension": ".md",
     }
+    multi_install_safe = True
 
     def build_exec_args(
         self,