Plugin framework maturation, reports overhaul, theming, and USB frontend repair

Framework:
- Per-plugin Alembic migration chains (ADR-008): every bundled plugin
  carries its own chain with a stamp-only anchor at the ownership cutover;
  new plugin schema lands in plugins/<name>/migrations/, never the core
  chain. Deploys add flask plugin upgrade-all. Fixed a latent bug in the
  shared alembic template (engine URL resolution) and taught the metadata
  filter to include FK-referenced core tables.
- Frontend plugin route gating (ADR-009): plugin routes carry meta.plugin;
  a disabled plugin's pages redirect to the dashboard via a cached,
  fail-open check against the new public GET /api/plugins/enabled.
- get_reports() plugin hook (contract 0.5.0 -> 0.6.0): plugins contribute
  report cards; warranty and toner cards moved off the hardcoded list.

Reports:
- Hub grouped by category with search; inline reports render at the top,
  are URL-backed (?report=id, back-button and deep links work), expose
  their server-side filter params as controls, and export CSV. Warranty
  and Toner pages gained CSV export.
- Deleted the dead legacy Warranty Status report (always-zero buckets
  from a retired column).

Theming and fonts:
- Inter (variable) bundled locally via @fontsource, replacing the Google
  Fonts Roboto import - air-gapped installs now render correctly; tables
  use tabular numerals.
- Optional brand_primary_dark_color, brand_accent_color,
  brand_sidebar_color settings applied to CSS vars at bootstrap.

USB frontend repair (views were reading a dead legacy shape):
- List/detail/form and the employee profile USB panels remapped to the
  real API shape (device_id/device_desc/checkinoutlog); employee panels
  now use /usb/checkouts endpoints; external-mode /usb/checkouts/active
  honors the badge filter; dead client methods pruned.

Also: warranties list page no longer requires login (matches app
convention); collector doc rewritten with a GE-Enforce integration guide
and paste-ready PowerShell reporter; ADR index and CHANGELOG updated.

Verified: 323 tests pass, naming/style green, frontend builds, plugin
migration dry-run green on scratch MySQL.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shopdb/plugins/migrations.py

@@ -158,8 +158,13 @@ class PluginMigrationManager:
             return None
 
     def has_pending_migrations(self, plugin_name: str) -> bool:
-        """Check if plugin has pending migrations."""
-        # Simplified check - would need DB connection for full check
+        """Check if plugin has any migration scripts on disk.
+
+        File-level check only (no DB): True when the plugin ships a
+        migrations/versions dir with at least one script. Used by
+        upgrade-all to decide whether the plugin participates in the
+        per-plugin Alembic flow at all.
+        """
         migrations_dir = self.get_migrations_dir(plugin_name)
         if not migrations_dir:
             return False
@@ -168,6 +173,35 @@ class PluginMigrationManager:
         if not versions_dir.exists():
             return False
 
-        # Check if there are any migration files
+        # Any migration files on disk?
         migration_files = list(versions_dir.glob('*.py'))
         return len(migration_files) > 0
+
+    def get_applied_revision(self, plugin_name: str) -> Optional[str]:
+        """Return the revision stamped in alembic_version_<plugin> in the DB,
+        or None if the plugin chain has never been stamped (or on any error)."""
+        migrations_dir = self.get_migrations_dir(plugin_name)
+        if not migrations_dir or not self.database_url:
+            return None
+        try:
+            from sqlalchemy import create_engine
+            from alembic.runtime.migration import MigrationContext
+
+            engine = create_engine(self.database_url)
+            with engine.connect() as connection:
+                context = MigrationContext.configure(
+                    connection,
+                    opts={'version_table': f'alembic_version_{plugin_name}'},
+                )
+                return context.get_current_revision()
+        except Exception:
+            return None
+
+    def has_unapplied_migrations(self, plugin_name: str) -> bool:
+        """True when the plugin's on-disk chain head is ahead of what the DB
+        has stamped. Compares the script head against alembic_version_<plugin>.
+        Best-effort: returns False when it cannot tell (no chain / no DB)."""
+        head = self.get_current_revision(plugin_name)  # script head on disk
+        if not head:
+            return False
+        return self.get_applied_revision(plugin_name) != head