docs(ai): document docker-exec pattern for hosts without native toolchains

The code-server LXC has bun and docker but no python/node/npm on PATH,
which left Codex unable to reproduce build/test commands. Adds a 6-line
block to PROJECT_CONTEXT.md showing the docker exec resolutionflow_{backend,frontend}
form, and updates the AGENTS.md "Tooling you do NOT have" line to point
Codex at it instead of suggesting toolchain installs.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

AGENTS.md

@@ -40,7 +40,7 @@ Prefer correct architecture over minimal diff. Flag "simpler approach" tradeoffs
 ### Tooling you do NOT have
 
 - **No GitNexus tools.** Use `grep -r`, `rg`, `git grep`, or `find` for code search. For blast-radius reasoning, grep call sites manually and read the files.
-- **No gstack slash commands** (`/review`, `/ship`, `/qa`, `/browse`, `/investigate`, `/design-review`, `/plan-*`). Run the equivalent work directly: `pytest` for tests, `npm run build` for frontend validation, manual PR description for review flow.
+- **No gstack slash commands** (`/review`, `/ship`, `/qa`, `/browse`, `/investigate`, `/design-review`, `/plan-*`). Run the equivalent work directly: `pytest` for tests, `npm run build` for frontend validation, manual PR description for review flow. If `python`/`npm` aren't on PATH, the host runs services in Docker — use the `docker exec resolutionflow_{backend,frontend} …` form documented in `.ai/PROJECT_CONTEXT.md` rather than installing toolchains.
 - **No `/codex` second-opinion command.** You are Codex.
 
 ### Git trailer