feat: peptide-geo-monitor v0.1.0 — AI-visibility dashboard

Add initial plugin implementation per the CTO engineering handoff
(geomonitor/threads/2026-06-ai-visibility-v1/01-cto-eng-handoff.md).

## What
- PGM_Probe_Provider interface + PGM_Probe_Result value object
- PGM_Perplexity_Provider (sonar via OpenRouter/CF AI Gateway)
- PGM_OpenRouter_Provider (GPT-search + Gemini-search, generic parameterised)
- PGM_Gateway_Client: shared HTTP + exponential-backoff retry (mirrors PRAB)
- PGM_Citation_Detector: domain extraction, is_cited(), get_our_position()
- PGM_Cost_Ledger: MTD cost from DB, can_afford() pre-check, hard monthly cap
- PGM_Probe_Runner: peptides×intents×models run, budget abort, in-run cache
- PGM_Table_Manager: pgm_ai_visibility dbDelta, schema-version, drop_table()
- PGM_Config: typed getters, seed_defaults() (12 peptides, 3 intents, 3 models)
- PGM_Cron: weekly pgm_weekly_probe schedule/clear
- PGM_Data_Collector + PGM_Dashboard_Panel interfaces (seam for future panels)
- PGM_Collector_Registry: singleton registry
- PGM_Ai_Visibility_Collector: trendline, standings, MTD cost (score formula)
- PGM_Ai_Visibility_Panel: proxy note, Chart.js trendline, standings table
- PGM_Admin_Page: GEO Monitor menu, Run now POST handler (nonce+capability)
- uninstall.php: DROP TABLE + DELETE pgm_* options + wp_clear_scheduled_hook
- Unit tests (6 files): citation detection, score calc, cost ledger + budget
  abort, provider response parsing (mock HTTP), cron, uninstall purge
- ARCHITECTURE.md, CONVENTIONS.md, CONTEXT.md (score formula), README.md,
  CHANGELOG.md — same-commit per DoD
- CI workflow: PHP lint (8.1/8.2/8.3) + PHPCS + 300-line check

## Security
- Secrets from wp-config constants only; none hardcoded
- manage_options + nonce on every admin action
- Input sanitized; output escaped

Agent-Session: geomonitor v0.1.0

tests/unit/test-uninstall.php

@@ -0,0 +1,101 @@
+<?php
+/**
+ * Tests for uninstall purge: table drop + options deletion.
+ *
+ * Exercises PGM_Table_Manager::drop_table() and verifies the uninstall
+ * script logic (simulated because it requires WP_UNINSTALL_PLUGIN).
+ *
+ * @package PeptideGeoMonitor
+ */
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../bootstrap.php';
+
+echo "=== PGM Uninstall Purge Tests ===\n";
+
+// ── Mock $wpdb to track DROP calls ──────────────────────────────────────
+
+$GLOBALS['pgm_test_state']['drop_calls'] = [];
+
+// Extend the stub to record DROP statements.
+global $wpdb;
+$wpdb = new class extends stdClass_wpdb {
+	public function query( string $sql ): bool {
+		if ( str_contains( strtoupper( $sql ), 'DROP TABLE' ) ) {
+			$GLOBALS['pgm_test_state']['drop_calls'][] = $sql;
+		}
+		if ( str_contains( strtoupper( $sql ), 'DELETE FROM' ) && str_contains( $sql, "pgm\\_" ) ) {
+			$GLOBALS['pgm_test_state']['options_deleted'] = true;
+		}
+		return true;
+	}
+};
+
+// ── Test: drop_table issues DROP TABLE IF EXISTS ─────────────────────────
+
+pgm_test_reset();
+$GLOBALS['pgm_test_state']['drop_calls'] = [];
+PGM_Table_Manager::drop_table();
+
+pgm_assert( ! empty( $GLOBALS['pgm_test_state']['drop_calls'] ), 'drop_table: DROP TABLE query executed' );
+$drop_sql = $GLOBALS['pgm_test_state']['drop_calls'][0] ?? '';
+pgm_assert( str_contains( strtoupper( $drop_sql ), 'DROP TABLE IF EXISTS' ), 'drop_table: uses DROP TABLE IF EXISTS' );
+pgm_assert( str_contains( $drop_sql, 'pgm_ai_visibility' ), 'drop_table: targets pgm_ai_visibility table' );
+
+// ── Test: create_table sets the schema_version option ────────────────────
+
+pgm_test_reset();
+PGM_Table_Manager::create_table();
+$schema_ver = get_option( 'pgm_schema_version' );
+pgm_assert_equals( PGM_SCHEMA_VERSION, $schema_ver, 'create_table: pgm_schema_version option set after create' );
+
+// ── Test: get_table_name returns prefixed name ───────────────────────────
+
+pgm_test_reset();
+$table = PGM_Table_Manager::get_table_name();
+pgm_assert_equals( 'wp_pgm_ai_visibility', $table, 'get_table_name: returns wp_ prefixed table name' );
+
+// ── Test: seed_defaults writes expected option keys ──────────────────────
+
+pgm_test_reset();
+PGM_Config::seed_defaults();
+
+pgm_assert( isset( $GLOBALS['pgm_test_state']['options']['pgm_monthly_budget_usd'] ), 'seed_defaults: pgm_monthly_budget_usd set' );
+pgm_assert( isset( $GLOBALS['pgm_test_state']['options']['pgm_peptides'] ), 'seed_defaults: pgm_peptides set' );
+pgm_assert( isset( $GLOBALS['pgm_test_state']['options']['pgm_prompt_intents'] ), 'seed_defaults: pgm_prompt_intents set' );
+pgm_assert( isset( $GLOBALS['pgm_test_state']['options']['pgm_models'] ), 'seed_defaults: pgm_models set' );
+
+// ── Test: seed_defaults does not overwrite existing values ───────────────
+
+pgm_test_reset();
+$GLOBALS['pgm_test_state']['options']['pgm_monthly_budget_usd'] = 99.0;
+PGM_Config::seed_defaults();
+pgm_assert_equals( 99.0, $GLOBALS['pgm_test_state']['options']['pgm_monthly_budget_usd'], 'seed_defaults: does not overwrite existing pgm_monthly_budget_usd' );
+
+// ── Test: default budget is PGM_DEFAULT_MONTHLY_BUDGET_USD ──────────────
+
+pgm_test_reset();
+PGM_Config::seed_defaults();
+pgm_assert_equals( PGM_DEFAULT_MONTHLY_BUDGET_USD, $GLOBALS['pgm_test_state']['options']['pgm_monthly_budget_usd'], 'seed_defaults: default budget = PGM_DEFAULT_MONTHLY_BUDGET_USD (5.0)' );
+
+// ── Test: default peptide count is 12 ───────────────────────────────────
+
+pgm_test_reset();
+$peptides = PGM_Config::get_peptides();
+pgm_assert_equals( 12, count( $peptides ), 'get_peptides: default seed has 12 peptides' );
+
+// ── Test: default prompt intent count is 3 ──────────────────────────────
+
+pgm_test_reset();
+$intents = PGM_Config::get_prompt_intents();
+pgm_assert_equals( 3, count( $intents ), 'get_prompt_intents: default seed has 3 intents' );
+
+// ── Test: default model count is 3 ──────────────────────────────────────
+
+pgm_test_reset();
+$models = PGM_Config::get_models();
+pgm_assert_equals( 3, count( $models ), 'get_models: default seed has 3 models' );
+pgm_assert( in_array( 'perplexity/sonar', $models, true ), 'get_models: perplexity/sonar in default models' );
+
+exit( pgm_test_summary() );