fix(#1582): derive phase-complete velocity from By-Phase table (idempotent) (#1655)

* fix(#1582): derive phase-complete velocity from By-Phase table (idempotent)

updatePerformanceMetricsSection blind-added summaryCount onto the prior velocity
total on every phase complete, so re-running phase complete on an already-complete
phase incremented the total each time (the sibling of #4, which fixed the Completed
Phases counter the same way). The velocity total is now derived as the sum of the
By-Phase table's Plans column AFTER the row upsert — re-completing a phase upserts
the same row, so the sum is stable; a hand-edited inflated total self-heals downward
to the true sum on the next completion. When the By-Phase table is absent the total
is left unchanged (no crash). Strengthens the misnamed 'idempotent' test (its comment
explicitly declined to assert velocity idempotency — the latent gap) and adds a
self-heal regression; corrects the #320 behavior-lock velocity assertion which had
encoded the blind-add (3 = 1+2 double-count) — the derived value is 2.

* chore(#1582): backfill changeset pr ref to 1655

* fix(#1582): velocity sum tolerates indented By-Phase rows (codex review)

Adversarial review (codex, gpt-5.5/high) flagged that byPhaseTablePattern's
data-row capture allows leading whitespace ([ \t]*\|), but the derive sum was
anchored at ^\| and would skip indented hand-edited/legacy rows — capturing them
in the table but silently undercounting. Align the sum regex (^\s*\|) with the
table capture's tolerance. Adds an indented-row regression. Two other codex
findings are pre-existing and out of scope: padded/unpadded phase dedup
(phaseRowPattern, identical in old code — derive yields the same value as the old
blind-add) and CRLF tables (the shared byPhaseTablePattern header requires bare
\n, so the upsert was already broken on CRLF; the fix changes stale-vs-
double-count, does not worsen it).

* fix(#1582): add verification fixtures to velocity tests under #1522 gate

Post-rebase onto next+#1548, the #1582 velocity tests (self-heal, indented-row) use
phase complete, which now fail-closes under #1522's canonical verification gate without a
passed *-VERIFICATION.md. Add writePassedVerification(tmpDir,'02-next','02') to both.

.changeset/zesty-elks-click.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 1655
+---
+**`phase complete` no longer double-counts Total plans completed velocity on re-run** — re-running `phase complete` on an already-complete phase incremented the velocity total each time (2 -> 4 -> 6 ...), because the metric re-read the cumulative total and blind-added the phase's plan count on every invocation. The total is now derived from the By-Phase table's Plans column (the same source the table upserts against), so re-completing a phase upserts the same row and the sum stays stable — and a hand-edited inflated total self-heals to the true sum on the next completion. (#1582)