Fix workspace URI paths with square brackets

[emecii]

Fixes #594.

Some editor clients send workspace file URIs with raw square brackets. java.net.URI rejects those characters, causing initialization to fail before the workspace can be opened. This change percent-encodes raw brackets only in the URI path before parsing, while preserving bracketed authorities.

Regression coverage exercises raw unmatched opening and closing brackets through the cross-platform URI-to-filename helper.

Validation:

• Red-before focused regression: 2 URISyntaxException errors
• clojure -M:test --focus eca.shared-test — 21 tests, 117 assertions
• bb test — 931 tests, 5,365 assertions
• Direct handlers/initialize reproduction with file:///tmp/work[one] succeeds
• Changed-file clj-kondo — 0 errors; only the existing always-true warning in shared.clj

Implementation assistance: OpenAI Codex.

• I added a entry in changelog under unreleased section.
• This is not an AI slop.