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

includes/core/class-pgm-config.php

@@ -0,0 +1,129 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Configuration helper: seed defaults and retrieve plugin settings.
+ *
+ * All mutable settings live in wp_options under the pgm_ prefix. This class
+ * provides typed getters (no magic values in call sites) and seeds the initial
+ * defaults on first activation.
+ *
+ * Who triggers: PGM_Activator::activate() for seeding; every component that
+ *               needs a setting reads through here.
+ * Dependencies: get_option(), update_option().
+ *
+ * @see CONTEXT.md          — Domain glossary: peptides, prompt intents, models.
+ * @see ARCHITECTURE.md     — §Config (options + defaults).
+ * @package PeptideGeoMonitor
+ */
+class PGM_Config {
+
+	/**
+	 * Seed the default option values on first activation.
+	 *
+	 * Uses add_option() so existing values are never overwritten on re-activation.
+	 *
+	 * Side effects: Writes multiple wp_options rows on first run.
+	 *
+	 * @return void
+	 */
+	public static function seed_defaults(): void {
+		add_option( 'pgm_monthly_budget_usd', PGM_DEFAULT_MONTHLY_BUDGET_USD );
+		add_option( 'pgm_peptides', self::default_peptides() );
+		add_option( 'pgm_prompt_intents', self::default_prompt_intents() );
+		add_option( 'pgm_models', self::default_models() );
+	}
+
+	/**
+	 * Get the monthly budget cap in USD.
+	 *
+	 * @return float Positive float; falls back to the plugin default.
+	 */
+	public static function get_monthly_budget_usd(): float {
+		$val = (float) get_option( 'pgm_monthly_budget_usd', PGM_DEFAULT_MONTHLY_BUDGET_USD );
+		return $val > 0.0 ? $val : PGM_DEFAULT_MONTHLY_BUDGET_USD;
+	}
+
+	/**
+	 * Get the list of peptide slugs/labels to probe.
+	 *
+	 * Each element is an associative array with 'slug' and 'label' keys.
+	 *
+	 * @return array<int, array{slug: string, label: string}>
+	 */
+	public static function get_peptides(): array {
+		$raw = get_option( 'pgm_peptides', self::default_peptides() );
+		return is_array( $raw ) ? $raw : self::default_peptides();
+	}
+
+	/**
+	 * Get the prompt intent templates.
+	 *
+	 * Each string may contain {peptide} as a placeholder.
+	 *
+	 * @return array<int, string>
+	 */
+	public static function get_prompt_intents(): array {
+		$raw = get_option( 'pgm_prompt_intents', self::default_prompt_intents() );
+		return is_array( $raw ) ? $raw : self::default_prompt_intents();
+	}
+
+	/**
+	 * Get the model identifiers to probe with.
+	 *
+	 * @return array<int, string>
+	 */
+	public static function get_models(): array {
+		$raw = get_option( 'pgm_models', self::default_models() );
+		return is_array( $raw ) ? $raw : self::default_models();
+	}
+
+	/**
+	 * Default set of ~12 high-interest peptides (slug + human-readable label).
+	 *
+	 * @return array<int, array{slug: string, label: string}>
+	 */
+	private static function default_peptides(): array {
+		return array(
+			array( 'slug' => 'bpc-157', 'label' => 'BPC-157' ),
+			array( 'slug' => 'tb-500', 'label' => 'TB-500' ),
+			array( 'slug' => 'mk-677', 'label' => 'MK-677' ),
+			array( 'slug' => 'cjc-1295', 'label' => 'CJC-1295' ),
+			array( 'slug' => 'ghrp-6', 'label' => 'GHRP-6' ),
+			array( 'slug' => 'ipamorelin', 'label' => 'Ipamorelin' ),
+			array( 'slug' => 'semaglutide', 'label' => 'Semaglutide' ),
+			array( 'slug' => 'tirzepatide', 'label' => 'Tirzepatide' ),
+			array( 'slug' => 'selank', 'label' => 'Selank' ),
+			array( 'slug' => 'semax', 'label' => 'Semax' ),
+			array( 'slug' => 'nad-plus', 'label' => 'NAD+' ),
+			array( 'slug' => 'aod-9604', 'label' => 'AOD-9604' ),
+		);
+	}
+
+	/**
+	 * Default prompt intent templates — three query styles per peptide.
+	 *
+	 * @return array<int, string>
+	 */
+	private static function default_prompt_intents(): array {
+		return array(
+			'what is {peptide}',
+			'{peptide} benefits and dosage',
+			'{peptide} reconstitution guide',
+		);
+	}
+
+	/**
+	 * Default models: Perplexity sonar (primary citation signal) + two
+	 * OpenRouter-routed search-capable models for breadth.
+	 *
+	 * @return array<int, string>
+	 */
+	private static function default_models(): array {
+		return array(
+			'perplexity/sonar',
+			'openai/gpt-4o-search-preview',
+			'google/gemini-2.0-flash-001',
+		);
+	}
+}