Untie hook scripts from .claude/ and consolidate under .scripts/

[breferrari]

Context

Discussion surfaced during the v6 ShardMind conversion (#70). Today the vault has two parallel script roots:

• .claude/scripts/ — hook implementations referenced by Codex's .codex/hooks.json and Gemini's .gemini/settings.json via ${*_PROJECT_DIR:-.}/.claude/scripts/.... Lives under .claude/ despite being shared infrastructure for all three agents.
• scripts/ — vault-level utilities (qmd-bootstrap.ts). Floats at vault root with no semantic anchor.

Two related problems:

1. Naming lies. .claude/scripts/ reads as Claude-specific, but Codex and Gemini both depend on it. A new contributor reasonably assumes deselecting Claude would be safe, when in fact every other agent's hook resolution breaks.
2. Loose scripts/ at root. Mixed alongside vault content folders (brain/, work/, reference/, …) it reads like vault content, not infrastructure. The v5.1 file explorer surfaces it as a top-level folder; QMD's md-only pattern doesn't index it but it's still odd in the user's vault tree.

Proposal

Consolidate both under a single .scripts/ dotfolder at vault root:

• .claude/scripts/ → .scripts/agent-hooks/ (or similar)
• scripts/qmd-bootstrap.ts → .scripts/qmd-bootstrap.ts

Update every reference site:

• .claude/settings.json (Claude hook commands)
• .codex/hooks.json (Codex hook commands)
• .gemini/settings.json (Gemini hook commands)
• .shardmind/hooks/post-install.ts (QMD_BOOTSTRAP_RELATIVE const)
• README.md (manual qmd setup invocation)
• vault-manifest.json::infrastructure[] (path glob updates)
• .obsidian/app.json::userIgnoreFilters (already covers .claude/ via #70; add .scripts/)

Constraints

This is a path rename, which the v6 contract gates on breferrari/shardmind#88 (rename migrations + shardmind adopt --from-version). The v6 acceptance criteria binding rule:

Verify zero path renames from v5.1. If any surface, rename migrations (shardmind#88) must ship first.

So this issue is blocked on shardmind shipping rename migrations. Once that lands, the obsidian-mind release that introduces this rename uses the migrations to keep existing v6 installs upgrading cleanly without losing user state.

Acceptance

• All hook command paths under .scripts/ instead of .claude/scripts/
• .shardmind/hooks/post-install.ts invokes .scripts/qmd-bootstrap.ts
• README's manual setup section uses the new path
• vault-manifest.json::infrastructure[] and .obsidian/app.json::userIgnoreFilters updated
• Migration entry added to .shardmind/shard-schema.yaml::migrations[] mapping the v6→v6.x renames
• CI green; clone-UX unchanged; shardmind update from older v6 to the rename-bumped version doesn't lose user state

Why not now

Currently blocked on shardmind#88. Tracked here so the rename ships in lockstep with the migration support.