selfhost: migrate tool sources to directory packages

Build w6a and w6l from package-main directories and expose the wcc backend through a narrow package API so w6c and wwdump no longer import implementation files. Retarget the remaining load-bearing fixtures and example sources to directory packages; retain the one intentional flat compiler collision as an explicitly composed raw unit.

examples/lisp/CLAUDE.md

@@ -5,7 +5,7 @@ backend rather than the C bootstrap one.
 
 ## Layout
 
-- `lispcore.ww`     interpreter module: types, lexer, parser, env,
+- `lispcore/`       interpreter directory package: types, lexer, parser, env,
                     eval, apply, printer, REPL. Everything the entry
                     point and the test driver consume is `export`-ed.
 - `lisp.ww`         entry point; `use lispcore;` + `main()`.
@@ -15,12 +15,9 @@ backend rather than the C bootstrap one.
                     runs the binary itself.
 - `test_*.lisp`     demo source files (`cat test_X.lisp | ./lisp`).
 
-The lispcore.ww + lisp.ww split exists so the tests can `use` the
-interpreter functions. Both files combine under the same module name
-(the directory's basename, `lisp`), because `ww`'s module resolver
-takes the *containing-directory* basename when finding a sibling.
-Cross-module type prefixes like `lispcore.value` don't resolve in the
-test — use the bare names.
+The lispcore/ + lisp.ww split exists so the entry point and tests import
+one canonical interpreter directory package. Cross-module type prefixes
+like `lispcore.value` don't resolve in the test — use the bare names.
 
 ## wwstage cgen workarounds at play
 

examples/lisp/Makefile

@@ -3,17 +3,14 @@
 #
 # Layout
 #   lisp.ww         entry point. `use lispcore;` + `main()` = repl().
-#   lispcore.ww     interpreter module. Types/functions are `export`-ed
+#   lispcore/       interpreter package. Types/functions are `export`-ed
 #                   so both lisp.ww and lisp_test.ww consume them via
 #                   the same `use lispcore;`.
 #   lisp_test.ww    in-process test driver, executed by `make test`
 #                   (which invokes `ww test`).
 #
-# `ww`'s module resolver uses the *directory's basename* as the module
-# name when finding `lispcore.ww` through `-I <dir>`. Passing the
-# absolute path of the current directory keeps that name stable
-# (otherwise `-I.` collapses to ".", and the cgen mangles symbols as
-# `..helper`, which then breaks the assembler).
+# The absolute include root makes `import lispcore` resolve the canonical
+# lispcore/ directory regardless of the caller's working directory.
 
 # Drive the wwstage cgen (w6c_ww) by default. The C-stage cgen has
 # unfixed silent-miscompilation traps that lispcore used to dodge by
@@ -25,7 +22,7 @@ W6CWW  := $(shell cd ../..; pwd)/out/bin/w6c_ww
 HERE   := $(shell pwd)
 WWENV  := WW_W6C=$(W6CWW)
 
-lisp: lisp.ww lispcore.ww
+lisp: lisp.ww lispcore/lispcore.ww
 	$(WWENV) $(WW) build lisp.ww -I $(HERE)
 
 # `ww test <file.ww>` in single-file mode discards extra args, so we
@@ -34,7 +31,7 @@ lisp: lisp.ww lispcore.ww
 test: lisp_test lisp
 	./lisp_test
 
-lisp_test: lisp_test.ww lispcore.ww
+lisp_test: lisp_test.ww lispcore/lispcore.ww
 	$(WWENV) $(WW) build lisp_test.ww -I $(HERE)
 
 # Demo programs in tree. `make demo` runs every test_*.lisp through

examples/lisp/lisp.ww

@@ -1,4 +1,4 @@
-// lisp — entry point. The interpreter lives in `lispcore.ww`; this
+// lisp — entry point. The interpreter lives in the `lispcore` package; this
 // file only wires it to `main()` so `ww build lisp.ww` produces the
 // REPL binary. The matching tests live in `lisp_test.ww` and pull
 // the same module via `use lispcore;`.

examples/lisp/lispcore/lispcore.ww

@@ -59,7 +59,7 @@
 //   - `acc /= d` / `acc += f` on f64 locals lower to `acc = d` (drop
 //     the OP). Write the explicit form `acc = acc OP d`.
 
-package lisp;
+package lispcore;
 
 import os;
 import rt;
@@ -1784,4 +1784,3 @@ export fn repl() i32 = {
 
 	return 0;
 };
-