feat: deterministic image composer — OG + square variants, branding, baked caption (v0.17.0)

Commit 2 (final scope) of the in-plugin editorial image pipeline
(ARCHITECTURE.md #21). A deterministic local composer now runs between
provider bytes and sideload: Image A yields a corner-marked featured
(1200x632) + branded OG (1200x630, teal band, logo, baked caption in
Poppins SemiBold) + square card (1080x1080, cream panel, Poppins Bold,
teal footer with the reverse lockup); Image B gets the corner mark only.

- Capability ladder: imagick (full compositing) -> wp_get_image_editor
  resize-only (unbranded, WARNING once) -> pass-through (WARNING once);
  probe cached in prautoblogger_image_compose_capability, fingerprinted
  by PHP version + imagick/gd presence so host flips auto-invalidate.
  compose() never throws; composition can never fail a publish.
- Variants sideloaded with a role filename suffix; attachment meta
  _prautoblogger_image_role + _prautoblogger_base_attachment_id; post
  meta _prautoblogger_og_image_id (frozen for the rebuilt SEO stage) +
  _prautoblogger_square_image_id. No cost-tracker rows ($0 local stage;
  duration logged on the image_composer channel).
- New Images settings: compose_enabled ('1'), compose_variants
  ('og,square'), featured_mark_enabled ('1') — read at point of use.
  Geometry ships as Layout defaults behind the
  prautoblogger_image_compose_layout filter.
- Vendored brand rasters (assets/brand) + bundled OFL Poppins faces
  (assets/fonts) for per-environment byte-stable output (stripImage +
  PNG date/time chunks excluded). Validated on Hostinger PHP 8.3.30 /
  ImageMagick 7.1.1-43: php -l clean on all touched files, double
  render byte-identical (sha256), exact variant geometry.
- Fix: featured/Image B alt text is the editorial caption (was the
  model name); model still persists in _prautoblogger_image_model.
- Image_Attacher extracted from Image_Pipeline (300-line compliance);
  sideloader gains an optional filename suffix param (back-compat '').
- Version 0.16.0 -> 0.17.0 + CHANGELOG + ARCHITECTURE.md #21 +
  CONVENTIONS.md composer guide in this commit. Unit tests: layout
  clamp boundaries, capability ladder, cache invalidation, attacher
  meta-linking, pipeline integration, imagick determinism (gated).

Agent-Session: engineer-prautoblogger-image-composer-20260611

assets/fonts/OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2020 The Poppins Project Authors (https://github.com/itfoundry/Poppins)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+http://scripts.sil.org/OFL
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.