Add thumbnail, template and technique columns to image-bearing queries

Six queries previously omitted image/template data from their /run_query
response, which v2 prod's SOLR backend used to surface. The geppetto-vfb
v2 processor already understands the canonical `[![alt](url 'alt')](ref)`
markdown form and the `[label](id)` template/technique markdown — these
were already in COL_HEADER_MAP (thumbnail->Images, template->Template_Space,
technique->Imaging_Technique). The gap was upstream: the Cypher functions
weren't fetching the channel/template/in_register_with paths.

Each affected function now adds:
  OPTIONAL MATCH (primary)<-[:depicts]-(channel:Individual)-[ri:in_register_with]->(:Template)-[:depicts]->(templ:Template)
  OPTIONAL MATCH (channel)-[:is_specified_output_of]->(technique:Class)
and returns `template`, `technique`, `thumbnail` columns using the
identical synthesis pattern at the existing canonical site
get_similar_neurons (line ~2469) and the term-info path
(vfb_queries.py:1965).

Functions changed:
  - get_similar_morphology_part_of      (NBLASTexp, neuron -> expression)
  - get_similar_morphology_part_of_exp  (NBLASTexp, expression -> neuron)
  - get_similar_morphology_nb           (NeuronBridge, neuron)
  - get_similar_morphology_nb_exp       (NeuronBridge, expression)
  - get_dataset_images                  (channel/template already in scope)
  - get_all_aligned_images              (re-bound anonymous nodes)

Schema entries updated to expose new columns via preview_columns:
  - SimilarMorphologyToPartOf, *Of_exp, NB, NB_exp
  - DatasetImages, AllAlignedImages

encode_markdown_links now covers 'template' and 'thumbnail' in each fn.

Verified python parse OK. No test changes — existing
test_similar_morphology.py asserts presence of ['id','name','score','tags']
(uses assertIn), which still holds.

Refs: VFB v2 migration to VFBquery — v2-dev was missing thumbnails on
~10 queries that prod rendered. See:
projects/geppetto-vfbquery-migration/VFBQUERY_THUMBNAIL_PATCHES.md
projects/geppetto-vfbquery-migration/VFBQUERY_API_AUDIT.md

Author: Robbie1977