SPEC.md: note number-stepper popover removal

Refresh §3 directory layout (drops number-stepper.js), insert
the post-Phase-17 removal entry in §9 with SHA e551705, prepend
the SHA to §13 git history, and tweak the §12 resume prompt
so a fresh session knows the slider popover is gone.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

SPEC.md

@@ -60,7 +60,6 @@ per-cell audit trail.
 │       └── js/
 │           ├── theme-init.js       # Phase 16: synchronous dark-class set from localStorage (no FOUC)
 │           ├── app.js              # site-wide; data-href click handler + hamburger menu + theme toggle
-│           ├── number-stepper.js   # Phase 17: custom popover stepper for [data-stepper] number inputs
 │           ├── sprint-planner.js   # /sprints/{id} Arbeitstage + task list
 │           └── sprint-settings.js  # /sprints/{id}/settings
 ├── src/
@@ -587,6 +586,22 @@ with a `BOOTSTRAP_ADMIN` audit row.
       pointerleave viewport-exit handler, and the focusout handler
       entirely — superseded.
 
+- [x] **Remove number-stepper slider popover** (`e551705`):
+      after seven iterations the click-to-open vertical-slider
+      popover added in Phase 17 still didn't behave reliably, and
+      the team prefers plain typed entry. Deleted
+      `public/assets/js/number-stepper.js`, dropped the
+      `<script>` tags from `views/layout.php` +
+      `views/sprints/present.php`, removed the `.stepper-popover`
+      CSS block from `assets/css/input.css`, and stripped
+      `data-stepper` attributes from `views/sprints/{show,
+      settings,present}.php` and the JS-built cell in
+      `sprint-planner.js::buildTaskRow`. Kept the `@layer base`
+      rule that hides native number-spinner arrows app-wide —
+      typing is now the only edit path on every number input;
+      ArrowUp/ArrowDown still steps via browser default. No
+      schema / route / PHP changes; tests untouched at 88 / 208.
+
 ### Upcoming
 
 Nothing scheduled.
@@ -656,7 +671,9 @@ Tell Claude:
 
 > Working on `/Users/achiappa/Development/claude_code_private/sprint_planer_web`.
 > Read `SPEC.md`, the git log, and `ACCEPTANCE.md`. Phases 1–17
-> are shipped (see §9) — nothing is currently scheduled. Outstanding
+> are shipped (see §9; the Phase-17 slider popover was later
+> removed — typed entry is now the only edit path on number
+> inputs) — nothing is currently scheduled. Outstanding
 > items are in §10 (mostly a human-run acceptance walkthrough in the
 > running container, plus the jQuery UI dark-mode cosmetic gap noted
 > there). If I ask you to plan or work a new phase, follow the
@@ -669,6 +686,7 @@ before acting — nothing here is load-bearing once it grows stale.
 ## 13. Git history (as of this writing)
 
 ```
+e551705 Remove number-stepper slider popover
 c5eef6a Docs: rename HANDOFF.md to SPEC.md, add admin manual, refresh README
 fd2f0df changed docker compose port
 761c4dd HANDOFF.md: note stepper close via direct listeners on Phase 17