feat: upgrade Docker images to Python 3.14 (experimental)

## Changes
- Update pyproject.toml: requires-python from <3.14 to <3.15
- Update all 5 Dockerfiles to use Python 3.14:
  - Builder stage: python3.12-trixie-slim → python3.14-trixie-slim
  - Runtime stage: python:3.12-slim-trixie → python:3.14-slim-trixie

## Files Updated
- src/backend/base/pyproject.toml
- docker/build_and_push_base.Dockerfile
- docker/build_and_push.Dockerfile
- docker/build_and_push_backend.Dockerfile
- docker/build_and_push_with_extras.Dockerfile
- docker/build_and_push_ep.Dockerfile

## Rationale
Python 3.14.5 was released on May 10, 2026. Upgrading to the latest
Python version should help reduce CVE vulnerabilities in Docker images.

## Testing Strategy
This is an experimental change to test Python 3.14 compatibility:
- Docker images will use Python 3.14
- CI/CD workflows still test on Python 3.10-3.13
- Nightly build will validate if dependencies work with 3.14
- Can be reverted quickly if issues are found

## Next Steps
- Monitor nightly build for failures
- If successful, update CI/CD workflows to add Python 3.14 to test matrix
- If failures occur, revert and investigate compatibility issues

docker/build_and_push.Dockerfile

@@ -9,7 +9,7 @@
 # 1. use python:3.12.3-slim as the base image until https://github.com/pydantic/pydantic-core/issues/1292 gets resolved
 # 2. do not add --platform=$BUILDPLATFORM because the pydantic binaries must be resolved for the final architecture
 # Use a Python image with uv pre-installed
-FROM ghcr.io/astral-sh/uv:python3.12-trixie-slim AS builder
+FROM ghcr.io/astral-sh/uv:python3.14-trixie-slim AS builder
 
 # Install the project into `/app`
 WORKDIR /app
@@ -75,7 +75,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 # RUNTIME
 # Setup user, utilities and copy the virtual environment only
 ################################
-FROM python:3.12-slim-trixie AS runtime
+FROM python:3.14-slim-trixie AS runtime
 
 
 RUN apt-get update \

docker/build_and_push_backend.Dockerfile

@@ -8,7 +8,7 @@
 ################################
 # BUILDER
 ################################
-FROM ghcr.io/astral-sh/uv:python3.12-trixie-slim AS builder
+FROM ghcr.io/astral-sh/uv:python3.14-trixie-slim AS builder
 
 WORKDIR /app
 
@@ -44,7 +44,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 ################################
 # RUNTIME
 ################################
-FROM python:3.12-slim-trixie AS runtime
+FROM python:3.14-slim-trixie AS runtime
 
 # Install minimal runtime dependencies
 RUN apt-get update \

docker/build_and_push_base.Dockerfile

@@ -10,7 +10,7 @@
 # 1. use python:3.12.3-slim as the base image until https://github.com/pydantic/pydantic-core/issues/1292 gets resolved
 # 2. do not add --platform=$BUILDPLATFORM because the pydantic binaries must be resolved for the final architecture
 # Use a Python image with uv pre-installed
-FROM ghcr.io/astral-sh/uv:python3.12-trixie-slim AS builder
+FROM ghcr.io/astral-sh/uv:python3.14-trixie-slim AS builder
 
 # Install the project into `/app`
 WORKDIR /app
@@ -77,7 +77,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 # RUNTIME
 # Setup user, utilities and copy the virtual environment only
 ################################
-FROM python:3.12-slim-trixie AS runtime
+FROM python:3.14-slim-trixie AS runtime
 
 
 RUN apt-get update \

docker/build_and_push_ep.Dockerfile

@@ -9,7 +9,7 @@
 # 1. use python:3.12.3-slim as the base image until https://github.com/pydantic/pydantic-core/issues/1292 gets resolved
 # 2. do not add --platform=$BUILDPLATFORM because the pydantic binaries must be resolved for the final architecture
 # Use a Python image with uv pre-installed
-FROM ghcr.io/astral-sh/uv:python3.12-trixie-slim AS builder
+FROM ghcr.io/astral-sh/uv:python3.14-trixie-slim AS builder
 
 # Install the project into `/app`
 WORKDIR /app
@@ -72,7 +72,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 # RUNTIME
 # Setup user, utilities and copy the virtual environment only
 ################################
-FROM python:3.12-slim-trixie AS runtime
+FROM python:3.14-slim-trixie AS runtime
 
 RUN apt-get update \
     && apt-get upgrade -y \

docker/build_and_push_with_extras.Dockerfile

@@ -9,7 +9,7 @@
 # 1. use python:3.12.3-slim as the base image until https://github.com/pydantic/pydantic-core/issues/1292 gets resolved
 # 2. do not add --platform=$BUILDPLATFORM because the pydantic binaries must be resolved for the final architecture
 # Use a Python image with uv pre-installed
-FROM ghcr.io/astral-sh/uv:python3.12-trixie-slim AS builder
+FROM ghcr.io/astral-sh/uv:python3.14-trixie-slim AS builder
 
 # Install the project into `/app`
 WORKDIR /app
@@ -72,7 +72,7 @@ RUN --mount=type=cache,target=/root/.cache/uv \
 # RUNTIME
 # Setup user, utilities and copy the virtual environment only
 ################################
-FROM python:3.12-slim-trixie AS runtime
+FROM python:3.14-slim-trixie AS runtime
 
 
 RUN apt-get update \

src/backend/base/pyproject.toml

@@ -2,7 +2,7 @@
 name = "langflow-base"
 version = "0.10.0"
 description = "A Python package with a built-in web application"
-requires-python = ">=3.10,<3.14"
+requires-python = ">=3.10,<3.15"
 license = "MIT"
 keywords = ["nlp", "langchain", "openai", "gpt", "gui"]
 readme = "README.md"