PR Vision v0.2.0: admin/settings interface + correctness fixes

Requirements 1-8 + all non-negotiables:

1. Model manager (CRUD): PRV_Model_Registry, prv_models v2 option, versioned
   idempotent migration from v0.1.x flat-string format, Settings page CRUD.

2. Per-model run-health: PRV_Model_Registry::update_health() after each run;
   health badges (Healthy/Retired?/Disabled/Unknown) in model table + dashboard.

3. Metric comparability: PRV_Config_Version stamps every run with config_version;
   save-bar warning on scoring-relevant changes; orphaned rows excluded by version.

4. Projected cost at save: PRV_Config::get_projected_cost(); over-cap warning;
   prv_last_run_truncated option + visible notice when cap hit mid-run.

5. Config surface: peptide set, intents, cadence (reschedules cron), budget cap;
   all validated + sanitized; next-run timestamp shown.

6. API-key three-state: not-defined / defined-ok / defined-failed; derived from
   ledger; never displays the key.

7. Run-lock: PRV_Run_Lock (transient); cron tick skips if locked; Run-now
   refuses with clear message; lock released in finally block.

8. Design fixes: dark-ink focus ring on bright fills; disabled-row full AA
   contrast (no opacity); toggle disabled on retired rows; save-bar-level
   warning (role=alert); chip text #B4BDC7 6.83:1 AA; keyboard-sortable headers
   (<button>+aria-sort); aria-live on Test chip; z-index:50 save-bar;
   run-now double-fire guard; @media print light overrides.

New: PRV_Upgrader (runs migrations on plugins_loaded, not just activation),
PRV_Config_Version, PRV_Run_Lock, PRV_Settings_Page, PRV_Settings_Renderer,
PRV_Model_Manager_Table, PRV_Model_Test_Ajax.

Tests: test-model-registry, test-run-lock, test-config-version,
       test-projected-cost, test-cron-reschedule (+ updated probe-runner,
       uninstall, bootstrap).

Schema: config_version INT column added via dbDelta (idempotent).
Uninstall: purges all v0.2 prv_* options + transients.

tests/unit/test-run-lock.php

@@ -0,0 +1,85 @@
+<?php
+/**
+ * Tests for PRV_Run_Lock: acquire/release/is_locked concurrency guard.
+ *
+ * @package PrVision
+ */
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../bootstrap.php';
+
+echo "=== PRV Run Lock Tests ===\n";
+
+// ── Test: acquire returns true when not locked ────────────────────────────
+
+prv_test_reset();
+prv_assert( PRV_Run_Lock::acquire(), 'acquire: returns true when lock is free' );
+
+// ── Test: is_locked true while acquired ──────────────────────────────────
+
+prv_assert( PRV_Run_Lock::is_locked(), 'is_locked: true immediately after acquire' );
+
+// ── Test: second acquire returns false (lock busy) ───────────────────────
+
+prv_assert( false === PRV_Run_Lock::acquire(), 'acquire: returns false when already locked' );
+
+// ── Test: release clears the lock ────────────────────────────────────────
+
+PRV_Run_Lock::release();
+prv_assert( false === PRV_Run_Lock::is_locked(), 'is_locked: false after release' );
+
+// ── Test: acquire succeeds again after release ───────────────────────────
+
+prv_assert( PRV_Run_Lock::acquire(), 'acquire: succeeds again after release' );
+PRV_Run_Lock::release();
+
+// ── Test: locked_since returns null when not locked ──────────────────────
+
+prv_test_reset();
+prv_assert( null === PRV_Run_Lock::locked_since(), 'locked_since: null when not locked' );
+
+// ── Test: locked_since returns non-null when locked ──────────────────────
+
+PRV_Run_Lock::acquire();
+$since = PRV_Run_Lock::locked_since();
+prv_assert( null !== $since, 'locked_since: non-null when locked' );
+prv_assert( $since >= 0, 'locked_since: >= 0 seconds' );
+PRV_Run_Lock::release();
+
+// ── Test: probe runner refuses when locked (skipped_error sentinel) ───────
+
+prv_test_reset();
+PRV_Model_Registry::run_migration_v2();
+$GLOBALS['prv_test_state']['options']['prv_peptides']       = [ [ 'slug' => 'bpc-157', 'label' => 'BPC-157' ] ];
+$GLOBALS['prv_test_state']['options']['prv_prompt_intents'] = [ 'what is {peptide}' ];
+
+// Pre-acquire the lock.
+PRV_Run_Lock::acquire();
+
+if ( ! defined( 'PRV_OPENROUTER_API_KEY' ) ) {
+	define( 'PRV_OPENROUTER_API_KEY', 'sk-or-test-key' );
+}
+if ( ! defined( 'PRV_CF_ACCOUNT_ID' ) ) {
+	define( 'PRV_CF_ACCOUNT_ID', '' );
+}
+if ( ! defined( 'PRV_CF_GATEWAY_ID' ) ) {
+	define( 'PRV_CF_GATEWAY_ID', '' );
+}
+
+$runner = new PRV_Probe_Runner( new PRV_Cost_Ledger() );
+$counts = $runner->run();
+
+// When lock is busy, skipped_error is -1 (sentinel) and probed is 0.
+prv_assert_equals( 0, $counts['probed'], 'run-lock: runner returns 0 probed when locked' );
+prv_assert_equals( -1, $counts['skipped_error'], 'run-lock: skipped_error is -1 sentinel when lock busy' );
+
+PRV_Run_Lock::release();
+
+// ── Test: runner releases lock even on exception (lock cleanup) ──────────
+
+prv_test_reset();
+PRV_Model_Registry::run_migration_v2();
+prv_assert( false === PRV_Run_Lock::is_locked(), 'run-lock cleanup: lock released after runner completes' );
+
+exit( prv_test_summary() );