Stability checkpoint — About 3-widget extraction (B-7-5 P1B, MR !113)

Phase B-7-5 P1B finalises the About-page split started in P1A. 3
substantive tabs extracted as widgets :
- AboutOverviewTabComponent  (217 LOC — hero SVG + tech badges)
- AboutInfraTabComponent     (155 LOC — port map + run.sh + ext svcs)
- AboutTechTabComponent      (52 LOC — A→Z technologies table)

11 small doc-pane shells stay inline in the parent template (each
~20 LOC of pure static link-out — extraction adds friction with no
behavioural isolation gain).

Counts :
- about.component.html : 613 → 251 LOC (-59 %)
- about.component.ts   : 92 → 77 LOC (post-P1A baseline)

Data imports :
- overview widget : docsBase passed as required input (parent owns URL)
- infra + tech widgets : import from sibling about-data.ts directly,
  no parent prop drill