Release v0.3.0: compiled forms — ReadPlan, owned BastDoc, LeafMeta, ValidationPlan, fingerprinting

Public API bump 0.2.0 -> 0.3.0 (the 030-compiled-forms plan is now
fully implemented; all eight phases landed).

- Cargo.toml: version 0.3.0. lib.rs re-exports complete (ReadPlan +
  sub-types, LeafMeta, OffsetEntry, ValidationPlan + sub-types).
- ADR-007 "Cost" rewritten to the Arc<ReadPlan> cost (15.7 ns) with
  the 0.2.0 "re-parse on demand" framing as a historical note
  (review #004 L2, the last loose end from that review).
- ADR-011/012 status blocks flipped to implemented; architecture
  README ADR table rows updated; layout-engine.md rewritten for the
  0.3.0 surface (engine-factory reader construction, OffsetMap
  OffsetEntry/LeafMeta/fingerprint section, owned BastDoc compute
  signature); SequentialReader module doc points at the engine
  factory. Reviews #004 and #005 flipped to closed.
- Bench re-run (alktty wire_vs_bast, 0.3.0 tree): read p64 98
  ns/chunk (parity with phase 2; hand-rolled 5.7 us/stream),
  layout_build 180 ns (was ~1.2 us — the phase-4 owned-doc cache
  removed the per-build re-parse, ~7x), sequential_reader_new 15.7
  ns, write p64 -3%, engine_compile unchanged (meta-schema
  validation dominates). No dedicated validate_bytes-stream bench:
  the phase-7 spot check (~0.2 us plan-validate vs ~0.6 us
  compile-per-call) stands; a dedicated bench is a follow-up if
  alkcall profiling motivates it.
- Downstream: alktty compiles against the path dep unchanged; alkcall
  has no dependency yet.

Verification (full block, all green): 474 tests; clippy -D warnings
clean; cargo doc zero warnings; wasm32 release build green; cargo
publish --dry-run clean at 0.3.0.

docs/architecture/decisions/007-packed-mode-read-factory.md

@@ -63,23 +63,26 @@ write-side.
 
 ### Cost
 
-`SequentialReader::new` clones the top-level struct's field schemas (a
-`Vec<(String, Value)>` of the `properties` entries) and clones the
-schema itself. This is cheap — a struct has a small number of fields
-(SFTP's largest packet has 5). The construction cost is negligible
-compared to the cost of reading a buffer.
+`SequentialReader::new(Arc<ReadPlan>)` is a refcount bump — 15.7 ns
+(measured, alktty `wire_vs_bast` bench, 0.3.0). The reader shares the
+engine's compiled [`ReadPlan`](011-compiled-read-plan-for-packed-mode.md)
+(the packed read-side compiled form) via `Arc` instead of cloning
+schema data; construction cost is negligible compared to reading a
+buffer. The engine holds the owned `BastDoc` (ADR-012 §2a) for the
+aligned materialize path and the one-shot `*::compile` paths.
 
-> **Note**: The "re-parse on demand" framing below (the read loop
-> re-parsing `BastDoc::new` per field) is the root cause of the 400x
-> read-path gap measured in
+> **Historical note**: the original 0.2.0 framing here ("re-parse on
+> demand" — the read loop re-parsing `BastDoc::new` per field) was the
+> root cause of the 400x read-path gap measured in
 > [review #004](../../reviews/004-performance-review.md).
-> [ADR-011](011-compiled-read-plan-for-packed-mode.md) (Proposed)
-> retires this framing by giving the packed read path a compiled
-> `ReadPlan`; the "Cost" section here and the
-> `src/engine.rs:112-115` doc comment will be updated in the
-> implementation commit per ADR-011's recommended order. The factory
-> decision itself (`sequential_reader() -> Option<SequentialReader>`,
-> owned fresh reader, consumer-driven cursor) is retained.
+> [ADR-011](011-compiled-read-plan-for-packed-mode.md) (implemented,
+> 0.3.0) retired it: the packed read loop walks `Arc<ReadPlan>` (2.27
+> µs/chunk → 98 ns/chunk), `sequential_reader()` is an `Arc::clone`,
+> and the owned `BastDoc` (ADR-012 §2a) removed the remaining
+> per-access re-parse sites in `read_field`/`write_field`/`validate_bytes`.
+> The factory decision itself (`sequential_reader() ->
+> Option<SequentialReader>`, owned fresh reader, consumer-driven
+> cursor) was retained unchanged.
 
 ## Consequences
 

docs/architecture/decisions/011-compiled-read-plan-for-packed-mode.md

@@ -2,7 +2,8 @@
 
 ## Status
 
-Accepted. Closes review #004 H1 + M1 (packed side) + L1 + L2;
+Accepted. Implemented in 0.3.0 (phases 1–2, 2026-09-02). Closes review
+#004 H1 + M1 (packed side) + L1 + L2;
 retires the "re-parse on demand" framing from ADR-007. A derisking
 POC on branch `readplan-poc` confirmed the `ReadPlan` shape covers
 every `BastType` arm in the current read loop before implementation

docs/architecture/decisions/012-plan-fingerprinting-and-m1-closure.md

@@ -2,8 +2,10 @@
 
 ## Status
 
-Accepted. Implemented (§3's `ValidationPlan`, 0.3.0 phase 7, 2026-08-31);
-bundles three pieces of work into the 0.3.0 release so the
+Accepted. Implemented in 0.3.0 — §3's `ValidationPlan` (phase 7,
+2026-08-31), §1's fingerprinting (phase 6), §2a's owned `BastDoc`
+(phases 3–4), §2b's `LeafMeta` (phase 5); all shipped 2026-09-02.
+Bundles three pieces of work into the 0.3.0 release so the
 crate ships one round of breaking changes, not two (or three). The
 three pieces: (a) fingerprinting `ReadPlan`/`OffsetMap`, (b) closing
 the deferred M1 sites via an owned `BastDoc` + `OffsetMap` `LeafMeta`,