release: Bux v1.0.0 language freeze

Bump compiler banners and package version to 1.0.0, activate SEMVER policy,
and add RELEASE_v1.0.0 notes. Fix closure auto-Drop leaking outer Array
drops into nested capture bodies (iter_hof). Fmt-clean examples/src for CI.

docs/RELEASE_v1.0.0.md

@@ -0,0 +1,55 @@
+# Bux v1.0.0 — Language Freeze
+
+**Date:** 2026-07-27  
+**Tag:** `v1.0.0`
+
+## What 1.0 means
+
+- **Language freeze** for public surface: syntax, stdlib APIs, and CLI that
+  scripts depend on follow `docs/SEMVER.md`.
+- **Normative spec:** `docs/LanguageRef.md`.
+- **Compilers:** bootstrap (`buxc`, Nim) and selfhost (`buxc2`, Bux) both target
+  the same language for the shipped feature set.
+- **Platform focus:** Linux primary; cloud/containers; cross/static/minimal
+  runtime. Windows is not a product platform.
+
+## Shipped surface (summary)
+
+| Area | Highlights |
+|------|------------|
+| Frontend | Pratt parser, recovery, macros (`macro!`, fragments, juxta/`tt`/`type`) |
+| Types | Generics (mono), tuples, fat `func` ABI, algebraic enums |
+| Ownership | `@[Checked]`, `@[Release]`, Drop/RAII, field-move + remaining Drop |
+| Concurrency | M:N tasks, channels, async |
+| Stdlib | Array/Map/Set/String/Iter HOF, Net/TLS, registry, Test |
+| Tooling | `fmt`, `test`, `doc`, `check`, LSP (separate versioning), DWARF `#line` |
+| Ecosystem | path/git/HTTP registry, lock + `--locked`, 4 apps, benches |
+
+## Explicitly *not* 1.0 blockers
+
+- True freestanding / bare-metal (`runtime_freestanding.c`, Cortex-M)
+- Operators-only token paste; full `Array<int>` in `:type` fragments
+- Windows product investment
+- LLVM / non-C backends
+
+## Upgrade notes from 0.5.x
+
+No mandatory source migration for projects that already build on late 0.5.x.
+New package scaffolds still default to package version `0.1.0` (package semver,
+not language version).
+
+### Fix included in 1.0.0
+
+- **Closure Drop isolation:** lowering a nested closure no longer emits
+  outer-function `Array_Drop` / auto-Drop on the closure’s return path
+  (broke `iter_hof` and any capturing HOF over droppable locals).
+
+## Verify
+
+```bash
+make build
+./buxc --version          # bux 1.0.0 (bootstrap)
+make test                 # full gate
+make selfhost             # buxc2
+# optional: make selfhost-loop
+```