Commit 1: editorial image prompt + style-template setting (#146)

* Commit 1: editorial image prompt + style-template setting

Pivot the image pipeline from the single-panel comic style to a text-free
editorial scientific illustration, and replace the Style Suffix setting with
an editable Style Template setting. Commit 1 of the in-plugin editorial image
pipeline (no composer yet; pipeline otherwise unchanged).

- New constant PRAUTOBLOGGER_DEFAULT_IMAGE_STYLE_TEMPLATE (brief §7 editorial
  template with the single {{ topic_summary }} token).
- New setting prautoblogger_image_style_template (textarea) replaces the
  Style Suffix field; single-token validation on save (brief A5); old
  prautoblogger_image_style_suffix mirrored to _deprecated for one cycle and
  not deleted (one-time migration prautoblogger_migrated_style_template_v0160).
- REWRITER_SYSTEM_PROMPT now emits a 1-2 sentence editorial topic/mechanism
  summary as the SCENE (no comic gag), keeping the CAPTION line for the
  unchanged HTML-caption-below-image path; scene/caption parsing contract
  preserved.
- New PRAutoBlogger_Image_Template_Filler substitutes the scene into the
  template's {{ topic_summary }} slot across all three entry points; strips
  control chars + clamps length (A5); degrades safely on missing token or
  empty summary so a blank/token-only prompt is never sent to the provider
  (A5/A6).
- Version bump 0.15.1 -> 0.16.0 + CHANGELOG + ARCHITECTURE.md updates.

Agent-Session: image-editorial-commit1

* style: auto-fix PHPCS violations via phpcbf

---------

Co-authored-by: peptiderepo <peptiderepo@users.noreply.github.com>

tests/bootstrap.php

@@ -67,11 +67,20 @@ if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_IMAGE_PROVIDER' ) ) {
     define( 'PRAUTOBLOGGER_DEFAULT_IMAGE_PROVIDER', 'runware' );
 }
 
-// Default image style suffix used by ImagePromptBuilder and settings UI.
+// Default image style suffix used by legacy ImagePromptBuilder paths / settings UI.
 if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_IMAGE_STYLE_SUFFIX' ) ) {
     define( 'PRAUTOBLOGGER_DEFAULT_IMAGE_STYLE_SUFFIX', 'Style: test infomercial style.' );
 }
 
+// Editorial style template (v0.16.0): default for prautoblogger_image_style_template.
+// Must contain exactly one {{ topic_summary }} token (brief A5).
+if ( ! defined( 'PRAUTOBLOGGER_DEFAULT_IMAGE_STYLE_TEMPLATE' ) ) {
+    define(
+        'PRAUTOBLOGGER_DEFAULT_IMAGE_STYLE_TEMPLATE',
+        "Editorial scientific illustration. Subject: {{ topic_summary }}. NO TEXT. NO PEOPLE. NO LOGOS. NO LABELS."
+    );
+}
+
 // WordPress database constants used in $wpdb queries.
 if ( ! defined( 'ARRAY_A' ) ) {
     define( 'ARRAY_A', 'ARRAY_A' );