feat(xce-harness-component): consolidate harness_unit_test binary

Relocate the 13 test files that lived inside controller_unit_test into
src/harness/testsuite/, add a new Unity runner (harness_test.c, modeled
on controller_test.c) carrying their extern/RUN_TEST entries, and
register the new harness_unit_test executable + suite in
src/harness/meson.build with an explicit build-order dependency on
xce_test (two of its tests spawn that binary over a pty).

Finish clearing the controller side: remove test_test_cli.c/
test_xcetest_process_entry.c from controller_unit_test_src and their
extern/RUN_TEST entries from controller_test.c, and remove the
temporary xce_test_controller_link symlink bridge task 1.1 added (no
longer needed now that both binaries build as siblings under harness/).

Verified: harness suite 132 Tests 0 Failures 0 Ignored; controller suite
1199 Tests 0 Failures 0 Ignored. 1199+132=1331 matches the pre-move
controller_unit_test baseline exactly (cross-checked against buglog
bug-1798/bug-1805).

Task 2.1 of xce-harness-component.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RLSNJhNoULvVcUhXEFafQC

.kiro/specs/xce-harness-component/tasks.md

@@ -20,7 +20,7 @@
   - _Requirements: 6.1_
 
 - [ ] 2. Core: migrate the five harness test binaries
-- [ ] 2.1 Consolidate the controller-embedded harness tests into a new binary and finish clearing them from the controller's own test binary
+- [x] 2.1 Consolidate the controller-embedded harness tests into a new binary and finish clearing them from the controller's own test binary
   - Physically relocate the 13 test files for this group into `src/harness/testsuite/`: the 11 whose `controller_unit_test_src`/`controller_test.c` references were already removed in task 1.1 (`test_waldump.c` through `test_xcetest_interrupt.c`, left on disk at their old path until now), plus `test_test_cli.c` and `test_xcetest_process_entry.c` (still validly part of `controller_unit_test` until this task)
   - Write a new Unity runner `harness_test.c` (modeled on `controller_test.c`) carrying all 13 `extern`/`RUN_TEST` entries; register the new `harness_unit_test` executable and its `meson test()` under suite `harness` in `src/harness/meson.build`; declare its build-order dependency on the `xce_test` executable target (two of its tests spawn that binary over a pty)
   - In the same task, remove `test_test_cli.c`'s and `test_xcetest_process_entry.c`'s entries from `controller_unit_test_src` and their `extern`/`RUN_TEST` lines from `controller_test.c` — the only two of the 13 not already removed in task 1.1 (`test_ctrlstatus`'s entry stays — it tests controller's own `ctrlstatus.c`)
@@ -102,3 +102,4 @@
 - **Task 1.1**: `test_test_cli.c`/`test_xcetest_process_entry.c` locate `xce_test` as a build-dir sibling via `resolve_xce_test_path()`. Since they still live in `src/controller/testsuite/` until task 2.1, a temporary `xce_test_controller_link` custom_target symlink bridge was added to `src/controller/meson.build` (documented in-code as removable once task 2.1 relocates both files). Task 2.1 must remove this custom_target and the `test()`'s `depends:` on it as part of that relocation.
 - **Task 1.1 gotcha**: a meson `custom_target` command's `@INPUT0@`/`@OUTPUT0@` tokens expand to build-root-relative paths, but a symlink's target string is resolved relative to the *symlink's own directory* at dereference time, not the invocation cwd or the string's own reference frame — using `@INPUT0@` directly as an `ln -sf` target from a different subdirectory produces a broken link. Use an explicit `../`-relative (or absolute) path instead.
 - **Build dir note**: this repo's default build dir resolves to `src/xce.build/` (relative to `src/tools/xce-build.sh`'s own cwd), not a bare `xce.build/` at the repo root.
+- **Task 2.1**: confirmed `resolve_xce_test_path()` (`/proc/self/exe` dirname + sibling lookup) needed zero code change once both `xce_test` and `harness_unit_test` build under the same `src/harness/meson.build` — they land in the same build-dir subdir automatically. Test counts cross-checked and consistent end to end: 1331 (pre-move) → 1228 (after task 1.1's 11-entry removal) → 1199 controller + 132 harness = 1331 (after task 2.1). Minor non-blocking nit for a future pass: `test_xcetest_process_entry.c`'s header comment still describes the old controller-embedded build layout — stale prose only, not a functional issue.