fix(omp): clamp OMP_AUTH_BROKER_URL/TOKEN, correct the env-allowlist docs

The docs claimed omp "has no documented vendor-key namespace of its own"
and "the multi-user clamp has nothing to gate" for omp — both false. Per
omp's own docs/environment-variables.md, it reads ~40 provider keys from
env (pi's known 34-key problem in the same shape), and its own knobs are
mostly PI_* (already globally allowlisted): PI_CONFIG_DIR,
PI_CODING_AGENT_DIR, PI_CODING_AGENT_SESSION_DIR, PI_SUBPROCESS_CMD,
PI_SHELL_PREFIX. The first three also move the ~/.omp tree
omp-session-resolver.ts/omp-transcript.ts hardcode, silently degrading
pinning/history — a known gap shared with pi, documented but not fixed
here.

The OMP_* prefix this PR adds brings in OMP_AUTH_BROKER_URL/
OMP_AUTH_BROKER_TOKEN, where omp resolves credentials from — the same
shape DEEPSEEK_BASE_URL is already dropped for in
clampEnvOverridesForOwner(). Add both to OWNER_CLAMPED_ENV_KEYS so a
non-granted owner in multi-user mode can't redirect them, and correct the
false claims in CLAUDE.md, docs/omp-integration.md, and the stale
resolveOmpHome() comment. Also documents omp's default
tools.approvalMode: yolo, which was previously unstated.

src/utils/omp-session-resolver.ts

@@ -50,7 +50,13 @@ export function mangleOmpWorkingDir(workingDir: string): string {
   return relative.replace(/\//g, '-');
 }
 
-/** `~/.omp` — no known env override exists (unlike DSH_HOME); revisit if omp adds one. */
+/**
+ * `~/.omp` — omp's own env overrides are mostly `PI_*` (shared with pi mode, already
+ * allowlisted in schemas.ts), and `PI_CONFIG_DIR` in particular can move this root.
+ * That is not honored here: a session with a redirected `PI_CONFIG_DIR` silently
+ * degrades pinning/history to omp's own ambiguous `--continue` instead of erroring,
+ * a known gap (found in Ark0N/Codeman#353 review) shared with pi and not fixed here.
+ */
 function resolveOmpHome(): string {
   return join(homedir(), '.omp');
 }