fix: streaming robustness — OpenAI parsing, error detection, reasoning content

Improves SSE parsing with raw JSON error detection, HTML response detection (for misconfigured endpoints), thinking/reasoning content from provider-specific delta fields, #[serde(default)] on streaming types for lenient deserialization, compact session boundary guard, and /team slash command. Adds install.sh convenience script.

rust/scripts/install.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+set -e
+
+# Build the release binary
+cargo build --release
+
+# Link to ~/.local/bin
+mkdir -p "$HOME/.local/bin"
+ln -sf "$(pwd)/target/release/claw" "$HOME/.local/bin/claw"
+
+echo "✓ Claw installed to ~/.local/bin/claw"