Fix Paperclip integration (identifier→issue_prefix) + add settings page

- Fix column name mismatch in paperclip_client.py and app.py: Paperclip's
  companies table uses `issue_prefix`, not `identifier`
- Fix _LEGAL_DB_URL to read from POSTGRES_URL env var (used in container)
- Add settings page (/settings) for managing tag → Paperclip company mappings
- Replace "תיק חדש" nav item with "הגדרות" (new case is on home page)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/paperclip_client.py

@@ -40,7 +40,7 @@ _FALLBACK_APPEAL_TYPE_TO_COMPANY = {
 }
 
 # Legal-AI DB URL for reading tag_company_mappings
-_LEGAL_DB_URL = os.environ.get(
+_LEGAL_DB_URL = os.environ.get("POSTGRES_URL") or os.environ.get(
     "DATABASE_URL", "postgresql://legal:legal@127.0.0.1:5432/legal_ai"
 )
 
@@ -76,11 +76,11 @@ async def create_project(
 
     conn = await asyncpg.connect(PAPERCLIP_DB_URL)
     try:
-        # Resolve prefix from company identifier in Paperclip DB
+        # Resolve prefix from company issue_prefix in Paperclip DB
         comp_row = await conn.fetchrow(
-            "SELECT identifier FROM companies WHERE id = $1::uuid", company_id,
+            "SELECT issue_prefix FROM companies WHERE id = $1::uuid", company_id,
         )
-        prefix = comp_row["identifier"] if comp_row and comp_row["identifier"] else "CMP"
+        prefix = comp_row["issue_prefix"] if comp_row and comp_row["issue_prefix"] else "CMP"
 
         # Check for existing project with this case number
         existing = await conn.fetchrow(
@@ -244,9 +244,9 @@ async def get_project_url(case_number: str) -> str | None:
         )
         if row:
             comp_row = await conn.fetchrow(
-                "SELECT identifier FROM companies WHERE id = $1::uuid", str(row["company_id"]),
+                "SELECT issue_prefix FROM companies WHERE id = $1::uuid", str(row["company_id"]),
             )
-            prefix = comp_row["identifier"] if comp_row and comp_row["identifier"] else "CMP"
+            prefix = comp_row["issue_prefix"] if comp_row and comp_row["issue_prefix"] else "CMP"
             return f"https://pc.nautilus.marcusgroup.org/{prefix}/projects/{row['id']}/issues"
         return None
     finally: