docs: remove temporary notes and fix onboarding drift

- delete TASKLIST.md and docs/design/handoff.md; the handoff content lives in README.md
- move docs/BOOTSTRAP-OWNERSHIP.md to docs/history/ and index it in docs/history/README.md
- point ONBOARD.md, docs/BORROW.md and the ticked TODO.md item at the new path
- ONBOARD.md section 9 no longer mentions TASKLIST.md
- ONBOARD.md section 3 and 4 markers are now `// ...` (line comments lost their colon)

verified from a clean build: make clean, make (fixpoint 376903 words), the
section 0-7 commands (section 4 after the marker fix), and the rejection suites. make check was
started but did not complete (stopped before it finished).

4 files changed, 2 insertions, 21 deletions

diff --git a/docs/BORROW.md b/docs/BORROW.md
index f270574..64a3183 100644
--- a/docs/BORROW.md
+++ b/docs/BORROW.md
@@ -45,7 +45,7 @@ the compiler functions, standard library, and language server currently run with
 
 the analysis runs with the existing parser, ownership checker, and lifetime records; it does not have a separate source parser or a complete path-sensitive proof. snapshots conservatively join branches and loops. low-level and unknown boundaries can hide behavior, so a quiet diagnostic set is not a whole-program safety proof. zc is single-threaded; shared closure cells do not define concurrent mutation rules.
 
-two completeness limits once stopped the compiler from compiling itself: an owner held in a local could not move into another local, and a local could not be lent to a global. the replacement and lend rules above close them; `docs/BOOTSTRAP-OWNERSHIP.md` keeps the record.
+two completeness limits once stopped the compiler from compiling itself: an owner held in a local could not move into another local, and a local could not be lent to a global. the replacement and lend rules above close them; `docs/history/BOOTSTRAP-OWNERSHIP.md` keeps the record.
 
 the maintained regressions cover these cases:
 
diff --git a/docs/design/handoff.md b/docs/design/handoff.md
deleted file mode 100644
index 0b08048..0000000
--- a/docs/design/handoff.md
+++ /dev/null
@@ -1,20 +0,0 @@
-# implementation notes
-
-this note summarizes implemented language and tooling features that were previously tracked across design documents. feature details live in the project readme and examples.
-
-## language and library
-
-- struct methods and static functions support typed parameters and return types. the existing untyped form remains available.
-- `src/lib/std.zc` groups helpers in structs of static functions, called with `Group.name(args)`. `Text`, `Bytes`, `Host`, `Arena` and `Buf` provide string, byte, host, arena and buffer helpers. linux `syscall` is host-only and bypasses vm checks.
-- tagged enums support payload members, constructors that return owned enum pointers, and `case member(fields)` bindings in ordinary `switch` statements. omitted members produce a warning when there is no `default`.
-- struct values can cross native calls on x86-64 sysv and linux arm64 aapcs64 for the interpreter, o3, llvm and jit paths described in the readme. apple arm64 remains unchecked.
-
-## language server
-
-the language server runs the compiler in check mode, so diagnostics and semantic highlighting use the same parser and symbol tables as compilation. hover supports declarations, parameters, locals, built-ins and documented keywords. it does not follow declarations reached through `include` yet.
-
-## optimization
-
-o3 remains the explicit way to request native regions; automatic tiering was dropped. llvm inlining and global copy propagation are implemented. see [tiering](tiering.md) for the rationale and [struct-by-value](struct-by-value.md) for native aggregate limits.
-
-the runtime memory map is generated from a preset. fixed code and compiler tables have finite capacity; the heap grows within the configured machine memory. see the project readme's memory map section for the current build controls.
diff --git a/docs/BOOTSTRAP-OWNERSHIP.md b/docs/history/BOOTSTRAP-OWNERSHIP.md
index 6cc61ce..6cc61ce 100644
--- a/docs/BOOTSTRAP-OWNERSHIP.md
+++ b/docs/history/BOOTSTRAP-OWNERSHIP.md
diff --git a/docs/history/README.md b/docs/history/README.md
index ead4aa0..1a91d19 100644
--- a/docs/history/README.md
+++ b/docs/history/README.md
@@ -54,3 +54,4 @@ the code folders are snapshots. they're not built or tested from here, the top l
 - 51 llvm-inline-stdlib: llvm inlining of o3 calls, stdlib text and num helpers, host syscalls through SYS_RAW, and the fuzz campaign's findings
 - 52 closures: closure calls work (the block is never run; a call into a heap closure goes through its entry word), captures chain through enclosing closures, and the closure test joins the suite
 - 53 typed source: every function, local and global in the compiler, the runtime and the language server is typed (zc0's image does not change), and the extension caches diagnostics by a sha256 of the tree they cover
+- BOOTSTRAP-OWNERSHIP.md: notes only (the two ownership rules that let the compiler compile itself, the partial fix before them, and the diagnostic that was reworded)