aws#2330)

Create ~/AGENTS.md with SageMaker Unified Studio context when the AWS
Toolkit activates on a remote SMUS Space. Uses HTML comment markers to
manage a section within the file, preserving any user content outside
the markers. Prompts the user before modifying an existing file that
doesn't have markers.

## Problem

When users connect to their space through their IDE, the code generated
through the IDE lacks context about the user's project. We are adding an
AGENTS.md and a context file that provides smus-specific context about
the user's space.

## Solution

When the AWS Toolkit activates on a remote SageMaker Unified Studio
Space (isSageMaker('SMUS-SPACE-REMOTE-ACCESS')), it runs
createAgentsFile() which creates AGENTS.md and links a separate
smus-context.md to it. The AI agent picks this up and gets SMUS-specific
context.

-> If AGENTS.md doesn't exist, we create smus-context.md and a new
AGENTS.md that just imports smus-context.md.
-> If AGENTS.md does exist and there is no import statement, we prompt
the user to modify their AGENTS.md with the import statement, and create
smus-context.md. We do not overwrite any of their changes.
-> If somehow smus-context.md exists but is not imported in AGENTS.md we
can still write to it, but we shouldn't touch the AGENTS.md. That would
mean a user doesn't want SMUS-context.md imported every time and we
should respect that.
->If AGENTS.md exists and has the import for smus-context.md, we just
write to SMUS-context.md without prompting the user.

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Co-authored-by: Ziwei Ba <ziwikiwi@amazon.com>

## Problem
These merge artifacts were discovered when comparing the
feature/smus-m2-kiro branch to the staging branch.
- Entry for aws.smus.refresh command in toolkit/package.json
- Duplicate amazonq changelog entry

## Solution
Removed the changes.

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Co-authored-by: Bhargav <bhargavavaradh@gmail.com>
Co-authored-by: Ziwei Ba <ziweichristina@gmail.com>

## Problem
- New feature requires change log

## Solution
- Added change log for new feature

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Co-authored-by: Bhargav <bhargavavaradh@gmail.com>
Co-authored-by: Ziwei Ba <ziweichristina@gmail.com>