Iter 15e: render is the exact inverse of parse — CLI hygiene

The CLI help text claimed `render` was symmetric to `parse`, but
`render` was wired to ailang_core::pretty::module (an older
human-pretty form) while `parse` consumed form (A). Two different
"text projections" coexisted under one name.

Fix: Cmd::Render and Cmd::Describe (both branches) now call
ailang_surface::print, the actual inverse of `parse`. Round-trip
gate via `ail render | ail parse` is now an e2e test in
crates/ail/tests/e2e.rs in addition to the existing unit-level
round-trip across all 25 fixtures in ailang-surface/tests.

Cleanup: `ailang_core::pretty::module` and its three private
helpers (`def_block`, `term_block`, `term_inline`) deleted —
~260 LOC of duplicate-purpose code removed. pretty.rs goes
from 457 to 196 LOC. Surviving surface is intentionally narrow:
manifest, type_to_string, pattern_to_string — the diagnostic
stringification used in error messages, where one-line ML
notation reads better than form (A)'s nested S-expressions.
Module-level doc rewritten to nail down the single-purpose
framing.

Tests: 89/89 (e2e +1, ailang-core unit -1 since the deleted
test exercised the deleted fn).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/JOURNAL.md

@@ -2606,3 +2606,67 @@ the CLI. Logged as 15e.
 **Queue update.** 15d done; remaining queue: 15e (CLI render/parse
 symmetry — small, just discovered), then `std_pair` if more stdlib
 is wanted, then 16a/16b language gaps.
+
+---
+
+## Iter 15e — `render` is the inverse of `parse` (CLI hygiene)
+
+**Trigger.** Discovered during 15d: `ail render | ail parse` did not
+round-trip. The help text claimed they were inverses but `render`
+called `ailang_core::pretty::module` (an old human-readable
+S-expression-ish form), while `parse` consumes form (A). Two
+different "text projections" lived in the codebase, one of them
+exposed via the CLI under a name that promised inversion.
+
+The form-(A) printer in `ailang_surface::print` was already correct
+and gated by `crates/ailang-surface/tests/round_trip.rs` across
+every fixture (25 modules at the time of writing) — it was simply
+not exposed at the CLI surface.
+
+**Changes.**
+
+1. `Cmd::Render` now calls `ailang_surface::print(&m)`. Help text
+   updated to state explicitly: form (A), exact inverse of `parse`,
+   round-trippable.
+2. `Cmd::Describe` (both single-module and `--workspace` branches)
+   likewise switched to `ailang_surface::print` so that "text view
+   of one def" means the same thing everywhere in the CLI.
+3. `ailang_core::pretty::module` deleted. With `module` gone its
+   helpers (`def_block`, `term_block`, `term_inline`) became dead
+   weight — also deleted. ~260 LOC of duplicate-purpose code gone;
+   `crates/ailang-core/src/pretty.rs` shrank from 457 to 196 LOC.
+4. The remaining surface of `ailang_core::pretty` — `manifest`,
+   `type_to_string`, `pattern_to_string` — is the diagnostic
+   stringification surface (used in error messages and the
+   `ail manifest` summary, where one-line ML notation is more
+   readable than form (A)'s nested S-expression). Module-level
+   doc rewritten to make this single-purpose framing explicit;
+   no more "pretty-printer" / "render" overloading.
+5. New e2e test `render_parse_round_trip_canonical` (in
+   `crates/ail/tests/e2e.rs`) gates the CLI shell pipeline:
+   shell out `ail render <fixture>` → write to tmp .ailx →
+   shell out `ail parse <tmp>` → assert canonical-byte equality
+   with the original fixture. The unit-level round-trip in
+   `ailang-surface/tests/round_trip.rs` covered the printer
+   function directly; this new test additionally guards the
+   CLI wiring.
+6. The `ailang_core::pretty` unit test `pretty_print_does_not_panic`
+   exercised the deleted `module` fn — removed. `manifest_contains_
+   type_and_hash` stays.
+
+**Doctrinal pin.** Form (A) is the only round-trippable text form.
+The diagnostic stringification in `ailang_core::pretty` is
+asymmetric and lossy by design — it exists for the *limited*
+purpose of sticking a type or pattern into an error message in
+human-friendlier shape than form (A). It does not roundtrip and
+must not be used as an authoring or persistence target. Any
+future add to it should add to that purpose, not back-fill toward
+"another text projection".
+
+**Tests: 89/89.** (e2e went from 31 to 32; ailang-core unit
+tests went from 11 to 10 — the deleted unit test exercised the
+removed fn. Net same.)
+
+**Cumulative state, post-15e.** No new language features. Two
+canonical text projections collapsed to one (form A). Internal
+cleanup; no behavioural change for any program in the repo.