v6.2.0 — sem-style CLI subcommands (#100)

Added

• tokensave_blame and tokensave_log — per-symbol git blame and history. Walks history via gix, parses each historical blob with tree-sitter, and matches the target symbol across commits via structural fingerprints. Tracks cross-file renames via a probe at the boundary. (#100)
• tokensave_diff — sem-style unified diff that orchestrates changelog, commit_context, and diff_context behind a single { from, to, changes } envelope. (#100)

Changed

• Renamed tokensave_outline → tokensave_entities to match sem terminology. The handler is unchanged; only the public MCP tool name (and CLI subcommand) is renamed. (#100)

Fixed

• blame/log/diff recognize new shader-language extensions. Adds .wgsl, .hlsl/.fx, and .metal to the language mapper so blame works on files added by #91.

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Closes #100.