fix(search_code): fuzzy mid-word matching + Luau/fuzzy live test coverage

Address the remaining real defects from the Luau/cs test reports. The wrapper-
level findings (dash-leading queries, context flag, no-match message, empty
query, path-is-file) were already fixed in earlier commits and verified through
the tool; the two genuinely-open items were engine-level, plus a test-coverage
gap (the patch-dependent behaviors were only exercised by live tests that
skip without a cs binary).

- Engine fix (docker/cs/fuzzy-distance.patch): cs's fuzzy `term~N` only scanned
  same-length windows, so it matched substitutions but never mid-word
  insertions/deletions — e.g. `computSlipAngle~1` (a dropped 'e') failed to find
  `computeSlipAngle`, contradicting cs's own "within 1 or 2 distance" docs.
  Now scan windows of length termLen±maxDist (true Levenshtein) and keep the
  best per offset. Updates one pre-existing cs test that encoded the buggy
  substitution-only behaviour and adds mid-word insert/delete cases. Passes
  cs's pkg/search + pkg/ranker suites; builds clean against the pinned commit.
- Provisioning: apply the new patch everywhere the Luau patch is applied —
  Dockerfile, Dockerfile.dev, packaging/PKGBUILD build() — so every install
  path (Docker bin/up, native code-search package via bin/service install)
  ships both patches.
- Tests: add skip-gated live tests for Luau declaration detection (function /
  local function / type / export type), only=usages exclusion, the Luau
  language tag, and fuzzy mid-word matching. New capability probes
  (findLuauCapableCs / findFuzzyCapableCs) run these only on a cs that actually
  has each patch and skip (never fail) on an unpatched/absent binary. Default
  suite: 600 pass / 12 skip; with a both-patched cs: 612 pass / 0 skip.
- Docs: UPSTREAM_CS_FUZZY_BUG.md documents the unreported upstream defect for a
  potential boyter/cs PR; CS_ARTIX_DEPLOY.md updated to reflect that
  sync-dispatch.sh now ships the code-search package (carrying both patches).

biome + tsc (core/api/frontend) + svelte-check all green.

1 files changed, 3 insertions, 1 deletions

diff --git a/packaging/PKGBUILD b/packaging/PKGBUILD
index 8918a30..878b15f 100644
--- a/packaging/PKGBUILD
+++ b/packaging/PKGBUILD
@@ -62,7 +62,8 @@ build() {
 	bun install --frozen-lockfile --production
 
 	# --- Build the patched `cs` code-search binary for the search_code tool ---
-	# Clone the pinned cs commit, apply the Luau declaration patch, and build a
+	# Clone the pinned cs commit, apply the Luau declaration + fuzzy-distance
+	# patches, and build a
 	# statically-linked binary. cs vendors its deps, so `go build -mod=vendor`
 	# needs no network beyond the clone. Mirrors the Docker cs-builder stage.
 	#
@@ -76,6 +77,7 @@ build() {
 	cd "${srcdir}/cs-src"
 	git checkout "${_cs_commit}"
 	git apply "${_projectdir}/docker/cs/luau-declarations.patch"
+	git apply "${_projectdir}/docker/cs/fuzzy-distance.patch"
 	CGO_ENABLED=0 GOFLAGS=-mod=vendor GOPATH="${srcdir}/gopath" GOCACHE="${srcdir}/gocache" \
 		go build -ldflags="-s -w" -o "${srcdir}/cs" .
 	"${srcdir}/cs" --version