.NET: Update Microsoft Foundry branding

[nicholasdbrady]

Motivation & Context

Microsoft renamed Azure AI Foundry to Microsoft Foundry as part of a product branding update. The repository still contained references to the old name across documentation, code comments, sample READMEs, and display strings. This PR updates those user-facing references so contributors and users see the current product brand consistently.

Description & Review Guide

• What are the major changes? Replaces user-facing Azure AI Foundry references with Microsoft Foundry across 224 files, including ADRs, Python and .NET sample READMEs, comments, display strings, CI workflow comments, and inline documentation. Technical identifiers such as package names, namespaces, API types, environment variables, and URLs are preserved.
• What is the impact of these changes? Documentation, samples, and displayed text now use the current product name. There are no API, schema, or runtime behavior changes.
• What do you want reviewers to focus on? Confirm the substitution is complete, that updated wording reads naturally in context, and that the workflow/comment/display-string updates are intentional.

Related Issue

No dedicated issue was filed for this trivial documentation and display-string branding update. A search of open issues and pull requests found no existing tracking item for this exact rename.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR is linked to an issue and there is no other open PR for this issue (see Related Issue above).
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[github-actions]

Python Test Coverage Report •

File	Stmts	Miss	Cover	Missing
packages/azure-contentunderstanding/agent_framework_azure_contentunderstanding
_context_provider.py	259	41	84%	78, 81, 199–202, 305–306, 308, 312–313, 316, 320, 405, 543, 547, 601, 651–652, 675, 677–680, 845, 849, 875–880, 882–887, 895, 904–905
_file_search.py	23	4	82%	58, 65, 69, 72
_models.py	38	1	97%	117
packages/core/agent_framework
_evaluation.py	722	75	89%	164, 172, 488, 490, 587, 599, 791, 794, 873–875, 880, 917–920, 976–977, 980, 986–988, 992, 1025–1027, 1083, 1119, 1131–1133, 1138, 1162–1167, 1260, 1338–1339, 1341–1345, 1351, 1390, 1738, 1740, 1748, 1758, 1762, 1807, 1825–1826, 1904, 1906, 1912, 1920, 1935, 1973, 1979–1983, 2015, 2038, 2046–2047, 2049, 2074–2075, 2080
observability.py	1011	87	91%	407, 409–410, 413, 416, 419–420, 425–426, 432–433, 439–440, 447, 449–451, 454–456, 461–462, 468–469, 475–476, 483, 660–661, 871, 875–877, 879, 883–884, 888, 926, 928, 939–941, 943–945, 949, 957, 1081–1082, 1317, 1592–1593, 1704, 1851, 1890–1891, 2073, 2358–2361, 2367, 2393–2394, 2422–2433, 2552, 2555, 2567, 2584, 2588–2589, 2592, 2598, 2707, 2924, 2926
packages/declarative/agent_framework_declarative/_workflows
_executors_agents.py	438	84	80%	95–96, 113–115, 156–157, 164, 192, 195–196, 204–205, 215, 226–231, 497, 535–537, 540, 556, 572–576, 600, 605, 695, 701–706, 713, 737–738, 747–749, 798–799, 807, 826, 933–936, 943–944, 953–954, 966–971, 975–976, 978, 983, 985, 989–992, 995, 997–998, 1001, 1009–1011, 1013, 1016–1017, 1019
packages/foundry/agent_framework_foundry
_memory_provider.py	93	0	100%
TOTAL	44478	5346	87%

Python Unit Test Overview

Tests	Skipped	Failures	Errors	Time
8817	33 💤	0 ❌	0 🔥	2m 2s ⏱️

[Copilot]

Pull request overview

Updates user-facing references from Azure AI Foundry to Microsoft Foundry across the repository to reflect current branding, while intentionally preserving technical identifiers (namespaces, package names, env vars, URLs).

Changes:

• Replaces “Azure AI Foundry” with “Microsoft Foundry” in docs/ADRs, sample READMEs, and inline comments across Python and .NET.
• Updates sample configuration/help text (env var descriptions, prompts, UI strings) to use the new brand.
• Refreshes a few .NET test/sample strings so prompts and skip reasons align with the new terminology.

Reviewed changes

Copilot reviewed 224 out of 224 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
TRANSPARENCY_FAQ.md	Updates provider/portal branding in Responsible AI transparency FAQ text.
python/samples/SAMPLE_GUIDELINES.md	Updates sample guidance and env var descriptions to Microsoft Foundry terminology.
python/packages/azure-contentunderstanding/agent_framework_azure_contentunderstanding/_context_provider.py	Updates docstrings for service endpoint branding (needs correction to CU endpoint wording).
python/packages/declarative/agent_framework_declarative/_workflows/_executors_agents.py	Updates docstring branding for declarative executor (should acknowledge retained InvokeAzureAgent naming).
dotnet/src/Shared/Samples/TestConfiguration.cs	Updates XML docstrings mentioning Foundry endpoint wording (minor grammar fix suggested).