fix(whatsapp,roles): self-heal legacy whatsapp_log schema; map underscore role aliases

CT115 (Mumuni relay #747) — two live-instance defects after PR #12:

1. GET /api/whatsapp/mock-log 500'd with a valid admin token:
   'no such column: whatsapp_log.message_text'. The model gained
   message_text/wa_message_id/ticket_number (and dropped command) in
   4afdc36 with no migration, so legacy DBs keep the (command, ...) shape.
   ensure_legacy_schema (startup, app/main.py) now adds the three missing
   columns idempotently and backfills legacy command bodies into
   message_text before dropping the obsolete NOT NULL command column, so
   both the mock-log read path and the ORM write path work on healed DBs.
   New producer/consumer regression (tests/test_whatsapp_log_legacy_heal.py)
   reproduces the exact OperationalError, then asserts 200 + data.

2. ROLE_ALIASES gap: underscore legacy roles (cs_rep, cs_manager,
   fm_dispatcher) were not mapped, so normalize_legacy_user_roles could not
   converge rows like user 18 (test@denya.com, role 'cs_rep') and the
   frontend stranded them on /tickets. Added the underscore aliases; tests
   assert normalize_role('cs_rep') == 'CS Rep' and a cs_rep row converges
   and authenticates.

app/core/roles.py

@@ -12,8 +12,9 @@ uses (PRD §4, ``app/services/seed.py``, the frontend nav in base.html):
 
 Legacy databases created under the pre-P0 open-registration builds can carry
 lowercase/nickname role strings (``technician``, ``cs``, ``fm``, ``ceo``,
-``admin``, ``superadmin`` …).  ``ROLE_ALIASES`` maps the *unambiguous*
-nicknames onto a canonical role so startup normalization (see
+``admin``, ``superadmin`` …) and underscore variants of the space-separated
+ones (``cs_rep``, ``cs_manager``, ``fm_dispatcher``).  ``ROLE_ALIASES`` maps
+the *unambiguous* nicknames onto a canonical role so startup normalization (see
 ``app/services/seed.py::normalize_legacy_user_roles``) can converge the data.
 
 ``admin`` / ``superadmin`` are deliberately NOT aliased: they are
@@ -52,10 +53,13 @@ ROLE_ALIASES: dict[str, str] = {
     "tech": TECHNICIAN_ROLE,
     "cs": "CS Rep",
     "cs rep": "CS Rep",
+    "cs_rep": "CS Rep",
     "cs representative": "CS Rep",
     "cs manager": "CS Manager",
+    "cs_manager": "CS Manager",
     "fm": "FM Dispatcher",
     "fm dispatcher": "FM Dispatcher",
+    "fm_dispatcher": "FM Dispatcher",
     "ceo": "CEO",
     "director": "Director",
 }

app/main.py

@@ -52,6 +52,47 @@ async def ensure_legacy_schema(conn) -> None:
                 text("UPDATE tickets SET reported_at = created_at WHERE reported_at IS NULL")
             )
             logger.info("Added missing tickets.reported_at column (legacy database)")
+
+    # whatsapp_log predates the real Meta webhook (the model gained
+    # message_text/wa_message_id/ticket_number and dropped `command` in commit
+    # 4afdc36 with no migration), so legacy DBs still carry the old shape and
+    # every read/write through the ORM 500s (no such column: message_text).
+    result = await conn.execute(
+        text("SELECT name FROM sqlite_master WHERE type='table' AND name='whatsapp_log'")
+    )
+    if result.scalar():
+        result = await conn.execute(text("PRAGMA table_info(whatsapp_log)"))
+        log_columns = {row[1] for row in result}
+        if "message_text" not in log_columns:
+            await conn.execute(
+                text("ALTER TABLE whatsapp_log ADD COLUMN message_text TEXT NOT NULL DEFAULT ''")
+            )
+            logger.info("Added missing whatsapp_log.message_text column (legacy database)")
+        if "wa_message_id" not in log_columns:
+            await conn.execute(
+                text("ALTER TABLE whatsapp_log ADD COLUMN wa_message_id VARCHAR(100)")
+            )
+            logger.info("Added missing whatsapp_log.wa_message_id column (legacy database)")
+        if "ticket_number" not in log_columns:
+            await conn.execute(
+                text("ALTER TABLE whatsapp_log ADD COLUMN ticket_number VARCHAR(30)")
+            )
+            logger.info("Added missing whatsapp_log.ticket_number column (legacy database)")
+        if "command" in log_columns:
+            # Legacy rows stored the message body in `command`, which the model
+            # no longer defines (NOT NULL, no default): any ORM insert omitting
+            # it would violate NOT NULL.  Preserve the old bodies in
+            # message_text, then drop the obsolete column to match the model.
+            await conn.execute(
+                text(
+                    "UPDATE whatsapp_log SET message_text = command "
+                    "WHERE (message_text IS NULL OR message_text = '') "
+                    "AND command IS NOT NULL AND command != ''"
+                )
+            )
+            await conn.execute(text("ALTER TABLE whatsapp_log DROP COLUMN command"))
+            logger.info("Dropped obsolete whatsapp_log.command column (legacy database)")
+
     result = await conn.execute(
         text(
             "UPDATE categories SET name = 'Missing Item' "