feat(ci): adopt estate CI + add PHPUnit suite from scratch (v1.2.0)

- Add PHPUnit 9.6 test suite (WP stubs, tests: stubs) — 40 tests across 4 files:
  MathTest: 25 tests covering all PRC_Math public methods and calculate()
  orchestrator with real peptide scenarios (BPC-157/TB-500/Semaglutide/MK-677/
  Ipamorelin) plus edge cases (zero water, negative inputs, floor rounding,
  rounding precision, mcg↔mg conversion).
  DefaultPresetsTest: 11 tests — all 8 expected slugs, required keys per preset
  (dataProvider), dose_unit validity, min<max range, source field, spot-checks.
  RestControllerTest: 7 tests — calculate() 200 + correct values (mcg+mg),
  get_presets() 200, get_preset() 200 for known slug / WP_Error for unknown.
  PresetProviderTest: 4 tests — fallback to defaults sans PR Core, slug key
  present, cache invalidation, idempotent invalidation.
- Add phpunit.xml.dist + tests/bootstrap.php (WP function/class stubs).
- Add composer test script: vendor/bin/phpunit --configuration phpunit.xml.dist.
- Add phpunit/phpunit ^9.6 + yoast/phpunit-polyfills ^2.0 to require-dev.
- Replace standalone ci.yml with thin caller to estate reusable workflow:
  uses: peptiderepo/peptide-e2e/.github/workflows/ci.yml@main
  with: tests: stubs, has_js: true
  permissions: contents: write (required for phpcbf commit-back)
  workflow_call (required for deploy.yml gate).
- deploy.yml unchanged — already gates on ./ci.yml + uses shared deploy-app.yml.
- Version bump 1.1.0 → 1.2.0.

Agent-Session: claude/adopt-ci-20260616

CHANGELOG.md

@@ -3,6 +3,32 @@
 All notable changes to Peptide Reconstitution Calculator are documented here.
 Format: [Semantic Versioning](https://semver.org/).
 
+## [1.2.0] — 2026-06-16
+
+### Added
+- PHPUnit test suite (WP stubs, `tests: stubs`) — 40 tests across four classes:
+  - `MathTest`: 25 tests covering all PRC_Math methods — concentration mg/mL,
+    mcg/unit, injection volume, syringe units, doses per vial, and the full
+    `calculate()` orchestrator with named peptide scenarios (BPC-157, TB-500,
+    Semaglutide, MK-677, Ipamorelin) plus edge cases (zero water, zero dose,
+    negative inputs, floor rounding, rounding precision).
+  - `DefaultPresetsTest`: 11 tests — collection count, all 8 expected slugs present,
+    required keys on every preset (via dataProvider), valid dose units, min < max,
+    source='default', and spot-checks on BPC-157 / Semaglutide / MK-677.
+  - `RestControllerTest`: 7 tests — calculate() 200 response + correct values for
+    mcg and mg dose units; get_presets() returns 200; get_preset() 200 for known
+    slug and WP_Error for unknown slug.
+  - `PresetProviderTest`: 4 tests — fallback to defaults without PR Core, all
+    presets have slug, cache invalidation, idempotent invalidation.
+- `phpunit.xml.dist` + `tests/bootstrap.php` (WP function/class stubs).
+- `composer test` script (`vendor/bin/phpunit --configuration phpunit.xml.dist`).
+- `phpunit/phpunit ^9.6` and `yoast/phpunit-polyfills ^2.0` in `require-dev`.
+
+### Changed
+- `ci.yml` replaced with thin caller delegating to estate reusable workflow
+  (`peptide-e2e/.github/workflows/ci.yml@main`; `tests: stubs`, `has_js: true`,
+  `permissions: contents: write`, `workflow_call` so `deploy.yml` gate works).
+
 ## [1.1.0] — 2026-04-26
 
 ### Changed