v1.12.3

<!-- Release notes generated using configuration in .github/release.yml at v1.12.3 -->

## What's Changed
### ✨ New Features
* feat(assistant): slash command menu and 100-step budget by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15149
* feat(agui): let callers opt out of graph state on the stream by @ogabrielluiz in https://github.com/langflow-ai/langflow/pull/15054
### 🐛 Bug Fixes
* fix(frontend): keep assistant reopenable mid-run by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15136
* fix(mcp): 404 for missing servers on GET and PATCH by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15130
* fix(frontend): report deleted MCP servers on edit by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15132
* fix(frontend): keep GB18030 characters in downloaded project filenames by @viktoravelino in https://github.com/langflow-ai/langflow/pull/15104
* fix(settings): keep database credentials out of settings errors and console tracebacks by @erichare in https://github.com/langflow-ai/langflow/pull/15147
* fix(opensearch): select k-NN method by engine instead of hardcoding disk_ann by @erichare in https://github.com/langflow-ai/langflow/pull/15142
* fix(export): keep global-variable bindings in flow and project exports by @erichare in https://github.com/langflow-ai/langflow/pull/15143
* fix(kb): scope OpenSearch and Chroma Cloud knowledge base storage by owner by @erichare in https://github.com/langflow-ai/langflow/pull/15148
* fix(mcp): stop project name prefix from blocking creation by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15144
* fix(mcp): connect SSE-mode servers over SSE by @Cristhianzl in https://github.com/langflow-ai/langflow/pull/15145
* fix(mcp): accept the tool names the MCP server publishes by @tarciorodrigues in https://github.com/langflow-ai/langflow/pull/15179
* fix(lfx): name real PyPI packages in provider install hints by @erichare in https://github.com/langflow-ai/langflow/pull/15189
* fix(security): pin IDN hosts by punycode and fail closed on DNS pin-map misses (LE-2544) by @erichare in https://github.com/langflow-ai/langflow/pull/15171
* fix(security): canonicalize tempfile._os/_sys re-exports in component code scanner by @erichare in https://github.com/langflow-ai/langflow/pull/15190
* fix(security): Scope frozen vertex result cache to executing principal by @erichare in https://github.com/langflow-ai/langflow/pull/15191
* fix(security): Enforce aggregate expanded-size limit for flow ZIP imports by @erichare in https://github.com/langflow-ai/langflow/pull/15196
* fix(security): Strip secret field values before publishing components to the Store by @erichare in https://github.com/langflow-ai/langflow/pull/15192
* fix(security): apply the caller-aware component policy to nested flow graphs by @erichare in https://github.com/langflow-ai/langflow/pull/15209
* fix(security): SSRF-validate OpenSearch and Chroma Cloud knowledge-base connection targets by @erichare in https://github.com/langflow-ai/langflow/pull/15197
* fix(security): eliminate cache deserialization RCE paths (H1-3982189) by @erichare in https://github.com/langflow-ai/langflow/pull/15199
* fix(connectors): call central SSRF guard in six unguarded connectors by @erichare in https://github.com/langflow-ai/langflow/pull/15200
* fix(security): resolve str.join in Agentic Assistant code scanner by @erichare in https://github.com/langflow-ai/langflow/pull/15195
* fix(security): close pathlib/io/codecs scanner bypass and stop validate_code from executing imports by @erichare in https://github.com/langflow-ai/langflow/pull/15201
* fix(security): proxy allow-listed modules in Python REPL to block transitive sys.modules escape by @erichare in https://github.com/langflow-ai/langflow/pull/15198
* fix(kb): SSRF-validate tenant-controlled OpenSearch and Chroma Cloud KB backend URLs by @erichare in https://github.com/langflow-ai/langflow/pull/15207
* fix(security): Guard provider base_url against SSRF and credential exfiltration by @erichare in https://github.com/langflow-ai/langflow/pull/15208
* fix(security): enforce fs_path containment in batch flow creation by @erichare in https://github.com/langflow-ai/langflow/pull/15206
* fix(security): close scan_code_security sandbox-escape bypasses (getattr dynamic-dunder + PyYAML) by @erichare in https://github.com/langflow-ai/langflow/pull/15202
* fix(security): close stdlib re-export bypass in component code scanner by @erichare in https://github.com/langflow-ai/langflow/pull/15204
* fix(security): de-duplicate the SSRF guards left by today's four-PR merge train by @erichare in https://github.com/langflow-ai/langflow/pull/15246
* fix(kb): require an operator-chosen destination for the network KB backends by @erichare in https://github.com/langflow-ai/langflow/pull/15244
* fix(security): block vars()/mapping dunder-key sandbox escapes in code scanner by @erichare in https://github.com/langflow-ai/langflow/pull/15194
* fix(security): close dynamic-getattr AST sandbox bypass in component code scanner by @erichare in https://github.com/langflow-ai/langflow/pull/15205
* fix(security): Enforce local-file-access containment on FileContentRetriever persistent_dir by @erichare in https://github.com/langflow-ai/langflow/pull/15193
* fix(security): Block jq $ENV/env server-environment disclosure in data components by @erichare in https://github.com/langflow-ai/langflow/pull/15203
* fix(checkpoint): drop model state that cannot be validated back on resume by @erichare in https://github.com/langflow-ai/langflow/pull/15241
* fix: Run Flow returns empty content when an Agent calls it as a tool by @erichare in https://github.com/langflow-ai/langflow/pull/15242
* fix(security): default LANGFLOW_RESTRICT_LOCAL_FILE_ACCESS to true by @erichare in https://github.com/langflow-ai/langflow/pull/15210
* fix(security): Block environment-provisioned provider credentials from tenant-chosen endpoints by @erichare in https://github.com/langflow-ai/langflow/pull/15211
* fix(mcp): stop Chinese project names from collapsing onto one server name by @viktoravelino in https://github.com/langflow-ai/langflow/pull/15141
* fix(lfx): read chat attachments through the storage service by @RostiBer in https://github.com/langflow-ai/langflow/pull/15249
* fix: honor CIDR allowlists for HTTP provider endpoints by @erichare in https://github.com/langflow-ai/langflow/pull/15262
* fix(deps): cap SQLModel before timezone storage changes by @erichare in https://github.com/langflow-ai/langflow/pull/15265
### 📝 Documentation Updates
* docs(security): warn when multi-user mode runs custom components unrestricted (LE-2533) by @erichare in https://github.com/langflow-ai/langflow/pull/15169
### 🛠 Maintenance Tasks
* chore: 1.12.3 dep upgrade by @Adam-Aghili in https://github.com/langflow-ai/langflow/pull/15245
* chore(bundles): bump lfx-google to 0.2.2 so the 1.12.3 release build can restamp by @erichare in https://github.com/langflow-ai/langflow/pull/15250

## New Contributors
* @RostiBer made their first contribution in https://github.com/langflow-ai/langflow/pull/15249

**Full Changelog**: https://github.com/langflow-ai/langflow/compare/v1.12.2...v1.12.3