feat(shopfloor): _tablet_session_audit helper for audit-log writes

Single source for sha256(session sid), ua trim, ip/acting_uid capture
from request. Used by unlock_session, lock_session, and force-lock cron.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_plating/fusion_plating_shopfloor/controllers/_tablet_session_audit.py

@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+"""Helper for writing fp.tablet.session.event rows from the new
+unlock_session / lock_session endpoints and the force-lock cron.
+
+Single source of truth for hashing the session sid, trimming the
+user-agent, and capturing forensic ip / acting_uid.
+"""
+import hashlib
+
+from odoo import fields
+from odoo.http import request
+
+
+def _sha256_session_sid(sid):
+    """Return sha256 hex digest of the session sid. Stored in the audit
+    log so DB leaks can't be replayed."""
+    if not sid:
+        return ''
+    return hashlib.sha256(sid.encode('utf-8')).hexdigest()
+
+
+def _trim_ua(ua):
+    """Trim user-agent to 256 chars (Odoo's standard Char width)."""
+    if not ua:
+        return ''
+    return ua[:256]
+
+
+def write_event(env, *, event_type, user_id=None, attempted_user_id=None,
+                session_id_hash=None, session_started_at=None,
+                session_ended_at=None, duration_seconds=None,
+                failure_reason=None, notes=None):
+    """Append an fp.tablet.session.event row. All writes sudo'd.
+
+    The acting_uid + ip + ua are pulled from the current request
+    automatically so callers never forget them.
+    """
+    vals = {
+        'event_type': event_type,
+        'user_id': user_id,
+        'attempted_user_id': attempted_user_id,
+        'session_id_hash': session_id_hash,
+        'session_started_at': session_started_at,
+        'session_ended_at': session_ended_at,
+        'duration_seconds': duration_seconds,
+        'failure_reason': failure_reason,
+        'notes': notes,
+        'acting_uid': env.uid,
+    }
+    if request:
+        vals['ip_address'] = request.httprequest.remote_addr or ''
+        vals['user_agent'] = _trim_ua(
+            request.httprequest.headers.get('User-Agent', '')
+        )
+    return env['fp.tablet.session.event'].sudo().create(vals)