enhance(#2142): archive quick tasks at milestone close-out (#3592)

* test(#2142): failing-first coverage for quick-task archival at milestone close-out

* enhance(#2142): archive quick tasks at milestone close-out

* fix(#2142): resolve review findings — readme injection, move/reset ordering, owned state write

* fix(#2142): fold archival under milestone namespace, expose index IR, dedupe reset decision

* test(#2142): assert archive-dir-relative summary path in index IR

* docs(#2142): backfill changeset pr number to 3592

* test(#2142): skip newline-fixture injection test on windows (control chars illegal in path names)

---------

Co-authored-by: sim <sim@local>

tests/emitted-drift-acks/2142-quick-task-archival.json

@@ -0,0 +1,6 @@
+{
+  "version": 1,
+  "paths": {
+    "cleanup.md": "#2142: adds retroactive quick-task archival — identify_quick_tasks step (target-milestone selection), dry-run summary + AskUserQuestion, archive_quick_tasks step using the narrow `milestone.archive-quick` command (not `milestone.complete --archive-quick`, which cannot be safely re-run against an already-completed milestone — see the step's own note), and success_criteria updates; the command was renamed from `quick.archive` to `milestone.archive-quick` (code-review FIX 1: fold under the existing `milestone` namespace, no new top-level command). 10319 -> 14941 bytes. (complete-milestone.md's #2142 growth is acknowledged in tests/emitted-drift-acks/3409-unreachable-guard-arms.json — two ack sources may never name the same path.)"
+  }
+}

tests/emitted-drift-acks/3409-unreachable-guard-arms.json

@@ -3,7 +3,7 @@
   "paths": {
     "gsd-phase-researcher.md": "#3409: guarded `cat \"$phase_dir\"/*-CONTEXT.md` against nullglob wiping the pattern to zero operands when no CONTEXT.md exists — a bare `cat` with no operands blocks reading stdin (hangs the agent) instead of the `2>/dev/null` guard ever firing, since a stalled read is not a failing exit. Now checks `${_CTX[0]}` is a real path before invoking cat. Growth is the array-guard idiom itself (+43 bytes).",
     "gsd-verifier.md": "#3409: same nullglob-hang fix as gsd-phase-researcher.md, applied to `cat \"$PHASE_DIR\"/*-VERIFICATION.md` in Step 0 — an absent VERIFICATION.md previously left a zero-operand `cat` blocking on stdin instead of falling through to first-verification mode. Growth is the array-guard idiom (+49 bytes). — #3206 append (merged into this fragment because two ack sources may never name the same path): +52 bytes, 49098 -> 49150 (2 under the LARGE cap). The growth is the literal fix for the term 5b used undefined: the compressed explicit-evidence definition inlined at 5b (+34 net on the rewritten line — the trailing honest-verifier cite there is dropped as superseded by the inline definition; honest-verifier.md stays cited at 5c) plus gsd-core/ path-prefix repairs on the two 404ing bare references/ cites at 5c (honest-verifier.md) and the MVP-mode section (verify-mvp-mode.md) (+9 each). Lazy extraction remains untakeable in this change: the large extractable blocks are content-pinned by tests that read the agent file directly (tests/verifier-behavior-unverified.test.cjs, tests/verification-overrides.test.cjs), so extraction is its own coordinated change.",
-    "complete-milestone.md": "#3409: guarded `cat .planning/phases/*-*/*-SUMMARY.md` — with `shopt -s nullglob` active in this block's preamble (#2962), zero matching phase summaries collapses the glob to nothing and a bare `cat` blocks reading stdin rather than producing empty output, wedging the milestone-completion review. Growth is the array-existence-check idiom (+73 bytes, two glob segments makes this longer than the single-glob sites).",
+    "complete-milestone.md": "#3409: guarded `cat .planning/phases/*-*/*-SUMMARY.md` — with `shopt -s nullglob` active in this block's preamble (#2962), zero matching phase summaries collapses the glob to nothing and a bare `cat` blocks reading stdin rather than producing empty output, wedging the milestone-completion review. Growth is the array-existence-check idiom (+73 bytes, two glob segments makes this longer than the single-glob sites). — #2142 append (merged into this fragment because two ack sources may never name the same path): +1605 bytes, 40498 -> 42103. The `archive_milestone` step now documents the opt-in `--archive-quick` quick-task archival flag (default OFF, deliberately NOT symmetrical with phase archival's default-ON posture), folds the AskUserQuestion decision for it into the SAME `milestone.complete` invocation (avoiding a redundant second call), and states the known bucket-all provenance limit.",
     "discuss-phase-assumptions.md": "#3409: replaced the unreachable `AUTO_MODE=$(gsd_run query check auto-mode --pick active 2>/dev/null || echo \"false\")` — `||` never fires because the query exits 0 with empty stdout when the field is absent, not a failure, so AUTO_MODE silently ended up empty rather than \"false\" — with a two-line capture-then-default (`AUTO_MODE=\"${AUTO_MODE:-false}\"`) that actually reaches the fallback. Growth is the extra default-assignment line (+19 bytes).",
     "plan-phase.md": "#3409: three sites. `AUTO_CHAIN` and `PHASE_REQ_IDS` get the same unreachable-`||`-fallback fix as discuss-phase-assumptions.md (empty-but-successful `gsd_run query` output never triggered `|| echo`, now uses `${VAR:-default}`); `PRIOR_SUMMARIES` additionally swapped `gsd_run query phases.list --pick summaries_total` for `--type summaries --pick count` since the old pick key produced the same unreachable-fallback failure mode for the walking-skeleton check. Net growth across the three sites is +39 bytes.",
     "session-report.md": "#3409: guarded `ls -la .planning/reports/SESSION_REPORT*.md 2>/dev/null || echo \"No previous reports\"` — with nullglob active, zero prior reports collapses the pattern to nothing and `ls -la` with no operands lists the current directory (a successful exit, wrong output) instead of failing into the `|| echo` fallback, so the report-existence check silently printed a directory listing. Replaced with an array-existence check that only lists when a real report file is present. Growth is the guard idiom (+58 bytes).",