feat(tools): add WebFetch and WebSearch parity primitives

Implement the first web-oriented Claude Code parity slice in the Rust tools crate. This adds concrete WebFetch and WebSearch tool specs, execution paths, lightweight HTML/search-result extraction, domain filtering, and local HTTP-backed tests while leaving the existing core file and shell tools intact.\n\nConstraint: Keep the change scoped to tools-only Rust workspace code\nConstraint: Match Claude Code tool names and JSON schemas closely enough for parity work\nRejected: Stub-only tool registrations | would not materially expand beyond MVP\nRejected: Full browser/search service integration | too large for this first logical slice\nConfidence: medium\nScope-risk: moderate\nReversibility: clean\nDirective: Treat these web helpers as a parity foundation; refine result quality without renaming the exposed tool contracts\nTested: cargo fmt; cargo test -p tools\nNot-tested: cargo clippy; full workspace cargo test

rust/crates/tools/Cargo.toml

@@ -7,6 +7,7 @@ publish.workspace = true
 
 [dependencies]
 runtime = { path = "../runtime" }
+reqwest = { version = "0.12", default-features = false, features = ["blocking", "rustls-tls"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"