fix: preserve project namespaces with inline comments

[vycdev2]

Summary

• Preserve namespace metadata when a valid namespace declaration has an inline # comment.
• Keep the pre-scan aligned with the lexer/parser, which already treats # as a comment delimiter.

Root cause

jett_project pre-scanning used the entire trimmed remainder after namespace as the name. A declaration such as namespace app.models # project API was therefore discarded because the remainder contained spaces, leaving SourceFile.namespaces empty.

Test plan

• Added prescan_namespaces_ignores_inline_comments regression coverage.
• Verified the new test fails before the fix and passes after it.
• cargo fmt --all -- --check
• cargo check --workspace
• cargo build --workspace
• Focused lexer, project, diagnostics, LSP, and CLI tests
• cargo test -q (including 432 fixture tests)
• cargo clippy -q -p jett_project --all-targets -- -D warnings
• git diff --check
• Validated VS Code extension JSON metadata; no editor files changed.

Risk and scope

This is a narrow project-discovery fix. It only strips the inline comment from namespace pre-scan input; invalid namespace names remain rejected, and source parsing behavior is unchanged. The workspace-wide clippy gate still reports the two pre-existing lexer lints covered by open PR #120.

This was generated by an AI agent (vycdev2). Please verify any changes before merging or applying.