nano: add the terminal editor leaf formula

[brandonpayton]

Purpose

Add GNU Nano 8.0 as a first-class Kandelo terminal-editor formula. It follows the normal Homebrew path: verified upstream source, a declared tap ncurses dependency, the real editor and data files, final fork instrumentation, and a real PTY edit workflow in brew test.

Dependency topology

Ncurses PR #8 is merged, and automattic/kandelo-homebrew/ncurses is Nano's explicit direct dependency. The registry manifest omitted this edge even though its build script resolved and linked ncurses; the formula records the actual dependency instead of relying on ambient registry state.

Formula contract

• Build the registry-authoritative Nano 8.0 source for wasm32.
• Link the exact tap ncurses interface and compiled fallback terminfo support.
• Use /home/linuxbrew/.linuxbrew/etc/nanorc as the guest-stable system configuration path.
• Disable optional browser, speller, libmagic, and NLS integrations that are not declared dependencies.
• Fork-instrument the final executable and install nano, rnano, documentation, manpages, and syntax data.
• Test version and option surfaces, stable runtime paths, and absence of keg/build-host paths.
• Use the tap-owned PTY runner to open, search, replace, write, and close a real file.

Source acceptance

The source formula may merge independently after a fresh source-only devil review. This PR contains no bottle block or Nano sidecar, and merging it does not claim that a bottle is published or installable.

Existing runtime evidence

Pre-final ABI 18 source and bottle-resolver runs passed the Node PTY workflow and equivalent Chromium workflow. The tested executable had ABI 18, imports only from env and kernel, all five wpk_fork_* exports, no Asyncify residue, and no host build paths in runtime payload files.

The previously reported local bottle SHA-256 b3440b94147780f7c9caf519a6f57c081b25d2050b46166dcc2dff865b0427a2 is historical evidence only and is rejected for publication.

Final source validation

The two Nano semantic commits and installed-tap loader commit were based on tap main at a3ede334ad27aac7c4d5826bac761b9faf768f20. Before merge, an independent source-only review verified a clean merge tree against then-current tap main at 594ad5514dd03b18ce0996cc0aaf6e081202f229.

• git range-diff reports all three commits unchanged from the already validated b9df206 restack.
• Every artifact-producing formula line after the support import is unchanged from reviewed head 672239c; the formula-tail SHA-256 is 2197e96ce0058dad3ccdacb21ae4df7b50c765b0ae3ce0bb97d739fc2c74e53e.
• Homebrew Ruby syntax passed.
• Formula-support tests passed: 21 runs, 186 assertions.
• brew style Formula/nano.rb reported no offenses.
• Literal Homebrew loading through installed Tap.fetch returned Nano; installed and branch support files both had SHA-256 f5f13ecbee24d8d87e50a6f457c5acd23c3fdee7af1cca1fb9f428bf9d021766.
• git diff --check passed and the worktree is clean.

No source build or runtime suite was rerun for this history/import-only restack. Current head is 1807a29f089446ed1680251c0d85a7adaf7856c5.

Bottle gates

Final bottle construction, publication, and installability claims remain gated on:

• sdk: reserve an 8 MiB main-thread shadow stack for linked programs kandelo#842 for the shared 8 MiB main-thread stack;
• Build fork instrumentation from the repository workspace kandelo#873 for repository-workspace fork instrumentation;
• sdk: centralize cross-compile function availability kandelo#874 for centralized cross-compile function availability;
• ci: isolate and verify Homebrew bottle publication kandelo#881 for caller-scoped, cache-isolated exact-branch publication;
• Reject stale Wasm artifacts with aliased ABI exports kandelo#882 for reliable aliased ABI-export validation;
• homebrew: publish tap-native formulas without registry duplicates kandelo#885 for tap-native formula publication;
• homebrew: preserve bottle compatibility for host build dependencies kandelo#887 where required for compatible host extraction/build dependencies;
• Test fork instrumentation output reproducibility across processes kandelo#888 for byte-reproducible fork instrumentation;
• homebrew: trust same-tap dependencies during bottle builds kandelo#890 for explicit trust of the same-tap ncurses dependency;
• tap PR ci: build branch bottles without granting publish authority #22 only if a branch-based pre-merge bottle dry run is needed;
• a final ncurses bottle published and poured first;
• an exact-head Nano build with reviewed sidecar, dependency receipt/provenance, and stock guest Node and Chromium PTY tests.

Automattic/kandelo#867 is merged ABI 18 baseline, not a pending gate. No platform ABI changes are made here. Firefox, WebKit, wasm64, and a final poured-bottle PTY run are not yet claimed.

[brandonpayton]

Independent devil's-advocate source-only review at 1807a29f089446ed1680251c0d85a7adaf7856c5: ACCEPT.

The review rechecked the declared GNU Nano 8.0 source and GPL-3.0-or-later licensing, direct ncurses dependency and upstream pkg-config overrides, stable guest sysconf path, final-binary fork instrumentation, installed Tap.fetch loader, and the PTY edit/search/replace/write workflow. Fresh dev-shell evidence passed Ruby syntax, Homebrew style, literal formula loading, formula-support tests (21 runs / 186 assertions), a clean current-main merge tree, and git diff --check.

The diff is source-only: one formula, with no bottle block, sidecar, archive, receipt, provenance metadata, or other binary artifact. Historical ABI 18 bottle inspection was used only as implementation evidence; trusted bottles must be rebuilt from the merged formula. No source-formula blocker remains.