fix: migrate wiki pages, fix broken links, and clean up Apport docs

[rkratky]

Description

• Replace dead bazaar.launchpad.net links with verified git.launchpad.net URLs (with +git/ path)
• Replace dead help.ubuntu.com/community links (Bugs/ApportRetraces, MOTU/School — both 404) with project docs references
• Migrate 3 wiki pages to project docs using moin2myst.py conversion script, with "migrated as-is" disclaimer on each:
  • apport-developer-how-to.md (from wiki.ubuntu.com/Apport/DeveloperHowTo)
  • error-tracker.md (from wiki.ubuntu.com/ErrorTracker) — includes 42 images downloaded from the wiki
  • apport-package-hooks.md (from wiki.ubuntu.com/Apport/PackageHooks)
• Update all wiki links in apport.md to reference the migrated project docs pages
• Remove dead SegvAnalysis/SegvReason/ProcMaps wiki links (404) — content already described inline
• Remove obsolete "Future plans" section (2009-era spec link)
• Fix conversion artifacts: mangled MoinMoin tables → proper Markdown tables, code block languages (none → python/bash/xml/text), image placeholders → actual images, heading hierarchy, _word_ italic artifacts

Related issue

• Fixes: docs: improvements to Apport content #540

Checklist

• I have read and followed the Ubuntu Project contributing guide
• My pull request is linked to an existing issue (if applicable)
• I have tested my changes, and they work as expected

[rkratky]

Note to self: even if LLMs might not be as useful as I'd hope in actually fixing docs bugs, they absolutely ace providing PR descriptions :-D