feat(harness): P3 — uniform ctx hook convention (rcust)

harness.meta.HookCtx (frozen): .domain, .base_url, .meta (RecipeMeta), .deps
(provisioned dep creds from $CCCI_DEPS_FILE or None), .op (current lifecycle op
or None); built via meta.hook_ctx() at each hook call site.

All recipe callables now take ctx: EXTRA_ENV(ctx), UPGRADE_EXTRA_ENV(ctx),
READY_PROBE(ctx), BACKUP_VERIFY(ctx), SCREENSHOT(page, ctx), ops.py pre_<op>(ctx).
Dict-valued EXTRA_ENV/UPGRADE_EXTRA_ENV unchanged (only the callable signature
moved). Call sites converted: deploy_app env shaping, perform_upgrade,
wait_ready_probes (gains op=), _perform_op BACKUP_VERIFY, screenshot.capture,
_run_pre_hook.

Legacy signatures fail FAST with a clear migration message: the registry carries
hook_params per hook key, enforced at meta.load() (MetaError names the old vs new
signature); ops.py pre-op hooks get the same check at the orchestrator call site
(meta.check_hook_signature) — no silent TypeError mid-run.

Migrated every in-repo user mechanically (17 ops.py files; cryptpad/lasuite-*/
mailu EXTRA_ENV; mumble+lasuite-drive READY_PROBE; ghost/discourse BACKUP_VERIFY)
— seeded values, probes and assertions byte-identical (domain -> ctx.domain;
keycloak pre_restore's meta arg -> ctx.meta).

Unit tests: hook_ctx field contract, ctx.deps from the run deps file, legacy-
signature MetaError (READY_PROBE/EXTRA_ENV/SCREENSHOT + pre-op checker), ctx
signatures accepted. Docs table regenerated (signature docs in key docs).

Verified on cc-ci: cc-ci-run -m pytest tests/unit -q -> 180 passed; scripts/lint.sh -> PASS.

tests/lasuite-docs/recipe_meta.py

@@ -15,7 +15,7 @@ HTTP_TIMEOUT = 600
 DEPS = ["keycloak"]
 
 
-def EXTRA_ENV(domain):
+def EXTRA_ENV(ctx):
     # abra's internal per-deploy convergence timeout (the recipe's TIMEOUT env, default 300s) is too
     # short for this 9-service stack on a COLD image cache (~9 large images: impress frontend/backend,
     # minio, postgres18, redis, docspec, y-provider). Cold pulls exceed 300s -> "deploy timed out 🟠".