feat(moments): skills and stored processes declare the moments they are for (milestone 458 step 5, #4923)

Loading a procedure now also reaches the moment it is for. Loading the
reporting procedure is a report; loading the release procedure is a delivery.

- Bundled skills: each SKILL.md declares `metadata: moments:`. The same
  declaration ships as Skill defaults (BUNDLED_SKILL_MOMENTS), because the
  server never sees the plugin's files. test_skill_moments holds the two
  together and pins the plugin name that qualifies the skill.
- Stored processes: `moments` on create_process and update_process, stored
  in the note's data and returned by get_process. A `scribe-proc-<slug>`
  load resolves its process through the sync manifest at load time. The
  moments are not copied into the stub, which would go stale mid-session.
- reachable_tools lists the skill loader whenever anything is mounted, since
  a process's moments are known only when it loads.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_moment_delivery.py

@@ -194,11 +194,17 @@ async def test_an_install_with_nothing_mounted_keeps_the_hook_off_the_wire():
 
 
 async def test_only_the_tools_whose_moments_carry_a_mount_are_listed():
-    assert await _reachable({"work.deliver"}) == ["bash"]
-    assert await _reachable({"work.finish"}) == ["update_milestone", "update_task"]
+    assert await _reachable({"work.deliver"}) == ["bash", "skill"]
+    assert await _reachable({"work.finish"}) == ["skill", "update_milestone", "update_task"]
     assert await _reachable({"skill.release"}) == ["skill"]
 
 
+async def test_the_skill_loader_counts_whenever_anything_is_mounted():
+    """A stored process declares its own moments, resolved only when it loads
+    — so a mount on any moment may be reached by loading a procedure."""
+    assert "skill" in await _reachable({"work.debug"})
+
+
 async def test_an_installs_own_mapping_and_removal_both_count():
     own = SimpleNamespace(tool="mcp__deploy__ship", match="", moment="work.deliver", effect="add")
     assert "ship" in await _reachable({"work.deliver"}, [own])