perf: auto-populate git context natively to avoid token waste

- Added get_git_context() to utils.rs using git2 to natively fetch branch, commit, and repo_name without CLI overhead.
- Wired native auto-population into LogCodeChangeHandler, LogErrorFixHandler, TechDebtHandler, TasksHandler, MilestonesHandler, AutoSessionCheckpointHandler, and HandoffMemosHandler.
- Eliminates the need for the LLM to waste repetitive background turns running git rev-parse HEAD and git branch --show-current via terminal shell commands just to feed the MCP logging tools.

server/src/handlers/tasks.rs

@@ -37,13 +37,13 @@ impl McpTool for TasksHandler {
                     description,
                     created_at: now,
                     updated_at: now,
-                    git_branch,
+                    git_branch: git_branch.or_else(|| crate::handlers::utils::get_git_context().0),
                     parent_id,
                     dependencies: deps,
                     acceptance_criteria: vec![],
                     expires_at: None,
                     namespace: namespace.unwrap_or_else(|| "default".to_string()),
-                    repo_name,
+                    repo_name: repo_name.or_else(|| crate::handlers::utils::get_git_context().2),
                     priority,
                     assigned_agent,
                     verification_command,
@@ -430,7 +430,7 @@ impl McpTool for MilestonesHandler {
                         description: description,
                         task_ids: task_ids.unwrap_or_default(),
                         deliverables: deliverables.unwrap_or_default(),
-                        repo_name,
+                        repo_name: repo_name.or_else(|| crate::handlers::utils::get_git_context().2),
                         ..Default::default()
                     })
                 });