phase 1: stop the bleeding — untrack 91 files, add verifier, harden CI

- Remove 91 tracked-but-gitignored files from index (sessions, plugin
  data/manifests, pycache, memory-changes, obsidian state, credential
  notes). Disk files preserved via --cached.
- Add .gitignore rules: .qmd/, .memory-index.lock, *.sqlite-wal/shm,
  13 credential note paths.
- Remove filename-blacklist ignore patterns (**/*password*.md etc.)
  that caught nothing and misfired on normal notes.
- Add .scripts/verify-vault.mjs: scans git-tracked files for key
  patterns (sk-*, AKIA*, gh[pousr]_*, glpat-*, xox*, BEGIN PRIVATE
  KEY) and 64-char hex in plugin .json files.
- Add verifier step to CI lint workflow before dependency install.

.obsidian/themes/AnuPpuccin/manifest.json

@@ -1,7 +0,0 @@
-{
-  "name": "AnuPpuccin",
-  "version": "1.5.0",
-  "minAppVersion": "1.6.0",
-  "author": "Anubis",
-  "authorUrl": "https://github.com/AnubisNekhet"
-}

.obsidian/themes/Minimal/manifest.json

@@ -1,8 +0,0 @@
-{
-	"name": "Minimal",
-	"version": "8.1.5",
-	"minAppVersion": "1.9.0",
-	"author": "@kepano",
-	"authorUrl": "https://twitter.com/kepano",
-	"fundingUrl": "https://www.buymeacoffee.com/kepano"
-}

.obsidian/themes/Typewriter/manifest.json

@@ -1,7 +0,0 @@
-{
-  "name": "Typewriter",
-  "version": "2.2.4",
-  "minAppVersion": "0.16.0",
-  "author": "crashmoney",
-  "authorUrl": "https://github.com/crashmoney"
-}