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.

runner/harness/generic.py

@@ -256,7 +256,7 @@ def perform_upgrade(
     # (target) version, so the base deploys minimally WITHOUT it and the upgrade adds it to COMPOSE_FILE
     # here, after the PR-head checkout (which ships the overlay) and before the chaos redeploy that
     # picks up the new .env. Dict or callable(domain)->dict. No-op for recipes without it.
-    upgrade_env = meta_mod.upgrade_extra_env(meta, domain)
+    upgrade_env = meta_mod.upgrade_extra_env(meta, meta_mod.hook_ctx(domain, meta, op="upgrade"))
     for k, v in upgrade_env.items():
         print(f"  upgrade-env: {k}={v}", flush=True)
         abra.env_set(domain, k, v)
@@ -272,7 +272,7 @@ def perform_upgrade(
         deploy_timeout=int(meta.DEPLOY_TIMEOUT),
         http_timeout=int(meta.HTTP_TIMEOUT),
     )
-    lifecycle.wait_ready_probes(meta, domain, timeout=int(meta.DEPLOY_TIMEOUT))
+    lifecycle.wait_ready_probes(meta, domain, timeout=int(meta.DEPLOY_TIMEOUT), op="upgrade")
     after = lifecycle.deployed_identity(domain)
     # Evidence (HC1): the chaos-version label = the deployed recipe commit; it should match the
     # PR-head we checked out — proving the upgrade deployed the code under test, not a published tag.