fix(uri-template): encode literal URI characters

[wang1408]

Problem

URI template literals containing non-ASCII characters or spaces were emitted and matched verbatim. A resource template such as file:///docs/café/{name} therefore could not match the percent-encoded URI sent over the wire.

Solution

Percent-encode literal template text with the existing RFC 6570 encoder during expansion and matching. RFC 3986 reserved characters and existing percent-triplets remain preserved. Added regression coverage for expansion and matching.

Testing

• uv run --frozen pytest -q tests/shared/test_uri_template.py (309 passed; baseline 307)
• uv run --frozen pytest -q tests/shared/test_uri_template.py tests/server/mcpserver/resources/test_resource_template.py (343 passed)
• uv run --frozen ruff check src/mcp/shared/uri_template.py tests/shared/test_uri_template.py (passed)
• uv run --frozen ruff format --check src/mcp/shared/uri_template.py tests/shared/test_uri_template.py (passed)
• uv run --frozen pyright src/mcp/shared/uri_template.py tests/shared/test_uri_template.py (passed)
• Full repository pytest was stopped after unrelated Windows permission and documentation-example environment failures; the changed-area tests above passed.

This contribution was prepared with AI assistance and manually verified.

Fixes #3526

[github-actions]

This PR has been closed automatically. This repo only keeps pull requests open when they come from a maintainer, or from a contributor a maintainer has assigned to the linked issue, and you aren't currently assigned to #3526.

If a maintainer assigns you to #3526, this PR reopens on its own and there's nothing more you need to do here. Assignment is a maintainer call based on capacity; comments that only ask to be assigned don't factor in. What does help is engaging on the issue itself by confirming the repro, explaining why it matters for your use case, or describing the approach you'd take.

You're welcome to keep pushing commits here (just avoid force-pushing, since GitHub can't reopen a rewritten branch), but that on its own won't get the PR reviewed or the issue assigned, and realistically most auto-closed PRs stay closed. There's no need to open a new PR either way.

CONTRIBUTING.md has the full reasoning, but in short:

• We're a small team with very little capacity to review community PRs right now.
• Many recent PRs are AI-generated with little human review, and reviewing one carefully still costs a maintainer as much time as it ever did. A well-described issue is usually more useful to us than the code.

Maintainers: reopen, remove missing-issue-link, or add bypass-issue-check to override.