Python: Remove --pre flag from pip install commands in READMEs

[Giles Odigwe (giles17)]

Motivation and Context

Addresses the first item in #5031: Remove --pre from all installs of released packages in READMEs.

As Agent Framework moves to v1.0, the --pre flag is no longer needed for released packages.

Description

• Removed --pre from all pip install agent-framework-* commands across 27 markdown files (package READMEs, sample READMEs, and the root README).
• Updated explanatory text in python/README.md and python/samples/AGENTS.md that referenced the --pre flag being required during preview.
• Kept --prerelease=allow flags in samples/05-end-to-end/hosted_agents/ as those reference third-party preview packages (azure-ai-agentserver-agentframework).

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? No

[Mark Wallace (markwallace-microsoft)]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
TOTAL	26994	3187	88%

report-only-changed-files is enabled. No files were changed during this commit :)

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
5341	20 💤	0 ❌	0 🔥	1m 23s ⏱️

[Copilot]

Pull request overview

Removes the --pre flag from Python pip install commands across READMEs and sample docs to reflect the transition away from preview-only installation guidance as Agent Framework approaches v1.0.

Changes:

• Removed --pre from pip install agent-framework* commands across Python docs/samples/packages.
• Updated explanatory text that previously stated --pre was required during preview.
• Left prerelease guidance in hosted end-to-end samples where third-party preview dependencies remain (per PR description).

Reviewed changes

Copilot reviewed 27 out of 27 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
python/samples/README.md	Removes --pre from sample prerequisites install command.
python/samples/AGENTS.md	Removes --pre and deletes preview-related explanation text.
python/samples/02-agents/providers/github_copilot/README.md	Removes --pre from GitHub Copilot provider install command.
python/samples/02-agents/declarative/README.md	Removes --pre from declarative package install and inline “Requirements” lines.
python/samples/02-agents/declarative/mcp_tool_yaml.py	Updates docstring prerequisites to remove --pre.
python/samples/02-agents/declarative/inline_yaml.py	Updates docstring prerequisites to remove --pre.
python/samples/01-get-started/README.md	Removes --pre from getting-started prerequisites.
python/README.md	Removes --pre from top-level and selective install commands and adjusts explanatory text.
python/packages/redis/README.md	Removes --pre from package install command.
python/packages/orchestrations/README.md	Removes --pre from package install command.
python/packages/openai/README.md	Removes --pre from package install command.
python/packages/ollama/README.md	Removes --pre from package install command.
python/packages/mem0/README.md	Removes --pre from package install command.
python/packages/github_copilot/README.md	Removes --pre from package install command.
python/packages/durabletask/README.md	Removes --pre from package install command.
python/packages/declarative/README.md	Removes --pre from package install command.
python/packages/core/README.md	Removes --pre from core + optional integration install examples.
python/packages/copilotstudio/README.md	Removes --pre from package install command.
python/packages/claude/README.md	Removes --pre from package install command.
python/packages/chatkit/README.md	Removes --pre from package install command.
python/packages/bedrock/README.md	Removes --pre from package install command.
python/packages/azurefunctions/README.md	Removes --pre from package install command.
python/packages/azure-cosmos/README.md	Removes --pre from package install command.
python/packages/azure-ai/README.md	Removes --pre from package install command.
python/packages/azure-ai-search/README.md	Removes --pre from package install command.
python/packages/anthropic/README.md	Removes --pre from package install command.
python/packages/a2a/README.md	Removes --pre from package install command.