feat(engine): support declaration body recovery and forward-decl resolution

[HarshK97]

Problem

1. When declarations were matched by name/receiver in matchDeclarations, only the root declaration nodes were mapped. If the inner body had substantial additions, deletions, or structural modifications, top-down and bottom-up passes could fail to map the body blocks directly, leaving them to be treated as complete deletions and re-insertions rather than modified blocks.
2. In languages supporting forward declarations or variable declarations sharing the same identifier as a subsequent full definition (such as Lua or C/C++), matchDeclarations could pair a small forward declaration against a full definition on the destination side, leaving the actual definition body unmapped.

What Changed

• Added Blocks node types to language rules schema in internal/treesitter/rules.go and defined block node types across 14 languages (including compound_statement, block, statement_block, and constructor_body).
• Added TestEveryLanguageBlocksAreValidSymbols in internal/treesitter/rules_test.go to validate all block symbol types against their respective Tree-sitter grammars.
• Resolved multiple candidate source declarations in matchDeclarations by subtree size delta, so full definitions map to full definitions and forward declarations do not steal destination functions.
• Implemented matchDeclarationBodies in internal/engine/matcher.go to locate corresponding block nodes within matched declarations, map them directly, and run Recover down their subtrees.
• Added unit tests covering cross-construct declaration matching with body recovery and forward-declaration resolution in internal/engine/declaration_test.go.
• Updated baseline test fixtures across Go, Java, Lua, PHP, Python, Rust, and Zig test suites where declaration bodies and their child statements now map cleanly in place.

Visual Comparison

• php_guzzle_handler_curl_multi

Before

After

[HarshK97]

Yesterday, Github was down. Now Github actions huh. Nice