feat(stuck): stuck-state pipeline overlay (cad-atlas#11)

Consumes mathias/cad#14's cad-stuck query directly — cad's app/domain
packages are public Go modules, so this reuses the exact tested
classification logic (import, not re-implementation) rather than
duplicating the taxonomy across two repos.

ApplyStuckOverlay (internal/atlas/stuck.go, fixture-tested) maps each
finding's category onto the existing 9-stage pipeline: armed_never_fired to
the human dispatch gate, claimed_never_ran/ceiling_hit/refire_loop/
near_attempt_cap to the one Execute stage (there is no separate Claim
stage), done_not_closed to the loop-back stage. Adds a StuckCount/
AwaitingCount badge per stage plus one Node per finding, linking out to the
underlying issue/comment — read-only, no controls, matching cad#14's own
constraint.

Two visual classes, kept deliberately distinct per the issue's own framing:
a coral 'N stuck' badge (needs intervention) vs a green 'N awaiting' badge
(a functioning control waiting on a human) — done_not_closed can never
render as a bottleneck.

Verified against the live estate: STAGE 05 shows 2 stuck (cobalt-dingo#30
ceiling_hit, cad-atlas#10 near_attempt_cap), STAGE 08 shows 5 awaiting
(cobalt-dingo #3/#7/#12/#16/#19 done_not_closed) — screenshotted via a
koala k3s Playwright job against a live-token server, matching cad#14's own
proven query output exactly.

go.mod: added git.d-ma.be/mathias/cad v0.10.0 (app/domain/adapters-gitearead
only — no mcp-chassis pulled in, that's only imported by cad's own cmd/cad).
Dockerfile: added the same GOPRIVATE/insteadOf fetch config mathias/cad's
own Dockerfile uses, now needed for this new private-module dependency.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Dockerfile

@@ -1,8 +1,18 @@
 FROM golang:1.26-alpine AS build
 WORKDIR /src
-RUN apk add --no-cache git
+# Fetch internal git-hosted Go modules (cad-atlas now depends on
+# git.d-ma.be/mathias/cad — cad-atlas#11, reusing cad#14's cad-stuck query
+# logic rather than duplicating the taxonomy) without going through
+# proxy.golang.org. Gitea returns http:// in its go-import meta tag, so
+# rewrite to https and bypass the module proxy + sumdb (mirrors mathias/cad's
+# own Dockerfile — same trick, same reason).
+RUN apk add --no-cache git && \
+    git config --global url."https://git.d-ma.be/".insteadOf "http://git.d-ma.be/"
+ENV GOPRIVATE=git.d-ma.be
+ENV GOPROXY=direct
+ENV GOSUMDB=off
 RUN go install github.com/a-h/templ/cmd/templ@latest
-COPY go.mod ./
+COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
 ARG VERSION=dev