feat(hir): link manifest predefines to source ranges

[hongjr03]

Summary

• preserve manifest source ranges for configured predefines from vide.toml
• expose manifest-backed predefine definitions through HIR preproc navigation/reference APIs
• load project manifests as non-source VFS files so IDE goto/hover can target them without passing them to slang diagnostics

Validation

• cargo fmt --check
• cargo test -p project-model -- --nocapture
• cargo test -p preproc
• cargo test -p hir preproc -- --nocapture
• cargo test -p ide preproc -- --nocapture
• cargo test -p vide manifest_defined_macro_powers_lsp_ide_features -- --nocapture
• cargo test -p vide project_manifest_is_not_diagnosed_as_systemverilog -- --nocapture
• cargo check -p ide
• cargo check -p vide
• git diff --check