feat: support git-backed subfolder vaults

[dieend]

Summary

Adds support for opening a Tolaria vault from a subfolder inside a larger Git repository.

Git discovery now resolves the parent worktree for a vault path, while Tolaria scopes file-facing Git behavior to the opened vault subtree. This allows multiple vaults or external systems to share one repository without Tolaria showing or committing unrelated sibling/root changes.

Note: Code fully generated by Codex GPT 5.5, and I don't have rust setup. Feel free to throw it away.

close #510

Why

I use Obsidian structure under openclaw agent, and would like to separate opening Tolaria and openclaw workspace.

Changes

• Added GitRepoContext to resolve:
  • worktree root
  • Git directory
  • vault-relative prefix inside the repo
• Updated Git-backed detection to use Git discovery instead of vault/.git.
• Scoped Changes, diffs, history, Pulse, conflict files, discard, conflict resolution, cache Git paths, and app commits to the active vault subtree.
• Kept pull/push/remotes as repo-level operations.
• Made init_git_repo a no-op when the selected folder is already inside a Git worktree, avoiding nested .git metadata.
• Added regression coverage for committing a nested vault while leaving outside repo changes untouched.
• Documented the behavior in Architecture/Abstractions and added ADR-0108.

[codacy-production]

Pull Request Overview

This PR cannot be merged in its current state as it contains no file changes, rendering it impossible to verify the claimed support for git-backed subfolder vaults. While Codacy results are nominally 'up to standards', the analysis is incomplete due to the missing diff.

A major concern is the author's admission that the code was fully generated by an AI model and has not been tested locally. This represents a significant risk for core repository operations. Additionally, none of the required acceptance criteria, such as the scoping of Git operations or the creation of ADR-0108, have been met.

About this PR

• Implementing architectural changes to Git handling using untested AI-generated code is a high-risk activity. The changes must be validated in a local Rust environment to ensure they do not corrupt Git repository structures.
• The PR does not contain any code changes or the required documentation (ADR-0108). Please ensure all files are correctly staged and pushed.

Test suggestions

• Opening a vault in a subfolder of an existing Git repository resolves the correct worktree root.
• Committing changes in a subfolder vault includes only files within that vault subtree, ignoring root-level or sibling changes.
• Syncing (push/pull) in a subfolder vault affects the entire parent repository as intended.
• Calling init_git_repo on a folder already inside a Git worktree does not create a nested .git directory.
• Git history and diff views correctly filter results to the vault-relative path.

Prompt proposal for missing tests

Consider implementing these tests if applicable:
1. Opening a vault in a subfolder of an existing Git repository resolves the correct worktree root.
2. Committing changes in a subfolder vault includes only files within that vault subtree, ignoring root-level or sibling changes.
3. Syncing (push/pull) in a subfolder vault affects the entire parent repository as intended.
4. Calling init_git_repo on a folder already inside a Git worktree does not create a nested .git directory.
5. Git history and diff views correctly filter results to the vault-relative path.

_{TIP Improve review quality by adding custom instructions
TIP How was this review? Give us feedback}

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Metrics 43 complexity · 0 duplication

Metric	Results
Complexity	43
Duplication	0

View in Codacy

AI Reviewer: first review requested successfully. AI can make mistakes. Always validate suggestions.

_{TIP This summary will be updated as you push new changes.}