fix(#4568): widen the phase-number regex to accept N-segment ids at 6 shell/markdown sites (#4646)

* test(#4568): pin the N-segment phase-grammar defect across all 6 shell/markdown sites

Manually traced against the current tree: the validating regex at
code-review.md rejects a 3-segment id (23.1.2), and execute-plan.md's
extraction truncates a 23.1.2-01-PLAN.md filename down to 1.2-01.

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

* fix(#4568): widen the phase-number regex to accept N-segment ids at all 6 shell/markdown sites

Widens `?` to `*` on the dotted-segment group at all 6 sites (byte-identical
behavior for 1- and 2-segment ids, character class unchanged): code-review.md,
code-review-fix.md, gsd-code-fixer.md, gsd-code-fixer.compact.md (validating
sites, plus their comment/error-message text), execute-plan.md's plan-filename
extraction, and plan-phase.md's --research-phase flag capture.

Also disambiguates the nsegment-phase-grammar test's plan-phase.md anchor,
which was matching an unrelated earlier `--research-phase` occurrence (line
77's generic-value capture) instead of the targeted site (line 131).

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

* chore(#4634): extend lint-phase-id-drift to ban the single-segment phase regex in workflows/ and agents/

Adds findSingleSegmentPhaseRegexDrift, banning the bounded
`[0-9]+(\.[0-9]+)?` shape (and its \d/doubled-backslash near-variants) on any
phase-carrying line across gsd-core/workflows/**/*.md,
gsd-core/references/**/*.md, and the newly-scanned agents/**/*.md, sanctioned
the same way as the existing shell-arith rule. Wired into scanAll; confirmed
zero violations against the real tree post-#4568 fix.

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

* docs(#4568): add Fixed changeset

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

* chore: regenerate conformance-tier manifests for the new test file

The emitted-attribution gate also flags 4 files growing: code-review-fix.md
(+21 bytes), code-review.md (+21 bytes), gsd-code-fixer.compact.md (+9
bytes), gsd-code-fixer.md (+6 bytes). The growth is the fix itself: each
site's validation regex widened from a bounded single-optional-dotted-segment
shape to the unbounded form, and the accompanying comment/error-message text
grew by a few characters to mention the new 3-segment example.

Emitted-Drift-Ack-Growth: code-review-fix.md — widens the phase-number validation regex from a bounded single-dotted-segment shape to accept N-segment ids, and adds a 3-segment example to the comment/error text (#4568)
Emitted-Drift-Ack-Growth: code-review.md — widens the phase-number validation regex from a bounded single-dotted-segment shape to accept N-segment ids, and adds a 3-segment example to the comment/error text (#4568)
Emitted-Drift-Ack-Growth: gsd-code-fixer.compact.md — widens the padded_phase validation regex from a bounded single-dotted-segment shape to accept N-segment ids, and adds a 3-segment example to the error text (#4568)
Emitted-Drift-Ack-Growth: gsd-code-fixer.md — widens the padded_phase validation regex from a bounded single-dotted-segment shape to accept N-segment ids, and adds a 3-segment example to the comment/error text (#4568)
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* chore(#4568): backfill changeset pr number to 4646

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

---------

Co-authored-by: sim <sim@local>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

.changeset/graceful-cats-hop.md

@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 4646
+---
+**A three-segment (or deeper) phase id no longer breaks phase-number validation or extraction** — code-review, code-review-fix, the gsd-code-fixer agent (both variants), execute-plan's plan-filename parsing, and plan-phase's --research-phase flag all re-derived a two-segment-max regex; a nested phase like 23.1.2 was rejected outright or silently truncated to the wrong id. All six sites now accept an arbitrary number of dotted segments, matching the canonical grammar. (#4568)