Refine contextual Project and Space popovers

[DeadWaveWave]

💡 Change Scope

• Small Change: Fast feedback, localized UI/logic, low-risk.
• Large Change: New feature, cross-boundary logic, runtime-risk (persistence, IPC, lifecycle, recovery).

📝 What Does This PR Do?

Refines Project and Space operation UI into compact, anchored contextual popovers.

• Local Project creation opens the directory picker directly and derives the project name from the selected folder.
• Remote Project creation uses a compact contextual flow.
• Space worktree create/archive/guard flows are anchored beside their triggering menu action instead of blocking the whole application.
• Only the affected Space enters a local frosted busy state while an operation is running.
• Nested branch selectors are owned transient layers, so selecting a branch no longer dismisses the parent popover.
• Popover geometry, control sizing, layering, light/dark themes, reduced motion, and initial measurement behavior are unified.
• Integrates the latest main dismissable-layer primitives while preserving transient parent ownership for nested portaled selectors.
• Documents the contextual operation-window contract and adds unit/E2E regression coverage.
• Repairs the recovery Worktree E2E fixture so it uses an owned temporary Git repository and never treats persisted application state as filesystem deletion authority.
• Synchronizes the recovery test with the new asynchronous Space-local busy state before launching terminals.

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🏗️ Large Change Spec (Required if "Large Change" is checked)

1. Context & Business Logic

Project and Space actions previously used app-level modal windows with inconsistent geometry and blocking behavior. The new behavior follows contextual menu semantics before confirmation, then switches only the target Space into a local running state after confirmation.

The recovery E2E previously treated disappearance of the editor as operation completion. With asynchronous local progress, that could race the Git operation and feed a stale source path into destructive cleanup. The fixture now owns an isolated temporary repository and waits for the durable Space directory transition before continuing.

2. State Ownership & Invariants

• Renderer operation state owns draft/running/error presentation for each Space.
• Worktree services and persisted workspace state remain the durable owners of filesystem and binding results.
• A draft popover never blocks unrelated application interaction.
• A nested transient layer never dismisses its owning popover.
• A running operation disables only its target Space and cannot leave a stale busy veil after completion or failure.
• Local Project naming is derived from the selected directory basename.
• E2E cleanup may delete only the temporary repository root created by that test.
• A persisted Worktree path is assertion input, never deletion authority.
• The created Worktree must be a canonical non-root descendant of the fixture Worktree directory and registered by git worktree list --porcelain -z.

3. Verification Plan & Regression Layer

• Unit coverage for anchored placement, nested transient-layer dismissal, Project flow, worktree phase transitions, and Space overlay state.
• Electron E2E coverage for branch selection, anchor geometry, dark/light themes, reduced motion, local Project creation, remote UI, and restart recovery.
• Full unit suite: 372 files passed, 1451 tests passed.
• Targeted UI Electron E2E: 4/4 passed.
• Repaired recovery Electron E2E: 3 consecutive runs passed.
• Post-merge Worktree branch-menu E2E: 3 consecutive targeted runs passed.
• Full unfiltered pnpm pre-commit: exit 0; staged Vitest 240 files passed / 3 skipped (868 tests passed / 3 skipped), native Electron terminal recovery 3/3 passed, and Electron E2E 262 passed / 47 conditionally skipped with zero retries.
• Repository integrity was checked after the repaired recovery case: HEAD, project files, node_modules, and clean Git status remained intact.

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✅ Delivery & Compliance Checklist

• My code passes the ultimate gatekeeper: pnpm pre-commit is completely green.
• I have signed the CLA if required (see CLA.md).
• I have included new tests to lock down the behavior.
• I have strictly adhered to the DEVELOPMENT.md architectural boundaries.
• I have attached a screenshot or screen recording (if this touches the UI).
• I have updated the documentation accordingly.

📸 Screenshots / Visual Evidence

Visual artifacts were captured locally for dark theme, light theme, the expanded branch list, and the opening motion. They can be attached to this draft during review.