feat(systems): a System names its files — path patterns stored, validated and matched (milestone 444 step 3, #4756)

A System gains path_patterns: globs relative to the repo root (* within one
directory, ** across any depth, a plain directory covering everything under
it). One service validates them for every door, so the web UI and MCP refuse
the same bad pattern with the same message. systems_for_paths resolves paths
to every active System that covers them, which step 4 (#4757) uses to deliver
an area's rulings when its files are touched.

- schema: systems.path_patterns JSONB NOT NULL default [] (migration 0113)
- service: normalize_path_patterns, path_matches, systems_for_paths
- routes + MCP create_system/update_system accept it; [] clears
- web UI: a Files field in the create and edit forms, patterns on the card
- backup carries it through export and restore
- using-scribe reflex 7: tagging work keeps a System's files current

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

src/scribe/mcp/tools/systems.py

@@ -9,6 +9,7 @@ tools are thin wrappers.
 Sentinels (match the milestone/task tool conventions):
   - name="" / description="" / color="" / status="" → "leave unchanged" on update
   - order_index=-1 → "leave unchanged" on update (0 is a valid order_index)
+  - path_patterns=None → "leave unchanged" on update ([] clears them)
 """
 from __future__ import annotations
 
@@ -167,6 +168,7 @@ async def create_system(
     name: str,
     description: str = "",
     color: str = "",
+    path_patterns: list[str] | None = None,
 ) -> dict:
     """Create a System (a reusable, self-describing subsystem/area) in a project.
 
@@ -195,11 +197,20 @@ async def create_system(
     under the System, so a ruling there reaches each session working in the
     area; a quote in a work log reaches one only if a search matches it.
 
+    `path_patterns` name the files that ARE the area: globs relative to the
+    repo root, `*` within one directory, `**` across any depth, and a plain
+    directory covering everything under it (`src/billing`,
+    `frontend/src/components/Billing*.vue`). The description says what the
+    area is for; the patterns say where it lives, so work touching those files
+    can be traced to the System without a search. Give them when the area's
+    files are known; a System without them still works for tagging.
+
     Args:
         project_id: The project this system belongs to (required).
         name: Short label (required).
         description: What the system is and how it's used — a name is rarely enough.
         color: Optional UI accent (hex), or empty.
+        path_patterns: The area's files as repo-relative globs, or omit.
 
     Duplicate-gated like the other creates: if a System with the same
     normalized name already exists in this project (archived included), the
@@ -237,7 +248,7 @@ async def create_system(
     system = await systems_svc.create_system(
         uid, project_id=project_id, name=name,
         description=description or None, color=color or None,
-        canonical_id=applied,
+        canonical_id=applied, path_patterns=path_patterns,
     )
     if system is None:
         raise ValueError(f"cannot create system in project {project_id} (no write access)")
@@ -307,6 +318,7 @@ async def update_system(
     color: str = "",
     status: str = "",
     order_index: int = -1,
+    path_patterns: list[str] | None = None,
 ) -> dict:
     """Update a System. Only explicitly provided fields change.
 
@@ -319,10 +331,14 @@ async def update_system(
     history. If the charter above it contradicts a ruling, fix that sentence
     in the same edit.
 
+    `path_patterns` also REPLACES the whole list, and `[]` clears it.
+
     Args:
         status: 'active' or 'archived'. Archive a system to retire it without
             losing history; archived systems hide from default lists.
         order_index: display position (0-based); -1 = leave unchanged.
+        path_patterns: The area's files as repo-relative globs (see
+            create_system). Omit to leave unchanged; [] clears them.
     """
     uid = current_user_id()
     fields: dict = {}
@@ -336,6 +352,8 @@ async def update_system(
         fields["status"] = status
     if order_index >= 0:
         fields["order_index"] = order_index
+    if path_patterns is not None:
+        fields["path_patterns"] = path_patterns
     system = await systems_svc.update_system(uid, system_id, **fields)
     if system is None:
         raise ValueError(f"system {system_id} not found or no write access")