fix(prompt-hook): cap injection under Claude Code's 10k inline limit (#1694) (#1769)

Claude Code persists hook stdout over 10,000 characters to a file and shows
the model a 2 KB preview. The prompt-hook MAX of 16,000 always hit that path
once explore filled the budget. Cap at 9,000 (exported + unit-tested) so the
payload lands inline, with headroom for the wrapper and projectPath nudges.

Lands the approach from #1695 with a testable helper.

Co-authored-by: Colby McHenry <colbymchenry@users.noreply.github.com>

CHANGELOG.md

@@ -234,6 +234,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 - **The Map covers a multi-root project.** A React Native app's `ios/` beside its `src/` — or any second root holding a fifth of the code — is now on the picture, one level deeper, instead of the map silently drawing only the larger root.
 
+- **The Claude Code prompt hook's context now arrives inline.** The hook capped its injection at 16,000 characters, but Claude Code shows hook output inline only up to 10,000 and otherwise persists it to a file with a 2 KB preview, so on any repo where explore filled the cap the model saw a file path and the first 2 KB. The cap is now 9,000 characters, under the limit with room for the wrapper. (#1694)
+
 - **`codegraph_explore` is loaded from the first prompt in Claude Code.** Claude Code defers every MCP tool behind a tool-search step, so a fresh session saw only the tool's name until the model searched for it, and the server's "call `codegraph_explore` instead of Read" had nothing loaded to act on. The tool now carries `anthropic/alwaysLoad` in its `_meta`, which exempts it on existing installs, and `codegraph install` writes `alwaysLoad: true` on the Claude Code server entry (re-run it to add the key). Copilot CLI's tool search holds MCP tools back the same way once ~30 tools are connected, so its entry now carries `deferTools: "never"`. (#1696)
 
 - Fixed a long-running `codegraph ui` session serving a symbol that a sync had already deleted. The viewer keeps one connection to your index open, and its in-memory lookup didn't notice when another process — your agent's sync, or `codegraph sync` — rewrote the file underneath it, so a symbol screen could keep showing a body with no callers while search correctly reported it had moved. Because a symbol's identity includes the line it starts on, this happened after almost any edit above it.