[cc] agentic conflict primitives v2 — ports, db_handles, git_locks, processes

[anipotts]

Source: deferred from v3 commit 6; current file-overlap detector is one primitive, real agentic conflicts span more

Problem

v3's file-overlap detector is `same path AND (same branch OR same worktree)`. Real agentic CC conflicts that aren't covered:

Conflict	Primitive needed
Both running dev server on same port	`ports` table tracking who has port N bound
Both running tests vs shared DB	`db_handles` table tracking which session has which DB connection
Both rebasing/pushing same remote branch	`git_locks` table; integration with `git rev-parse` checks
`.git/index.lock` ownership	Filesystem lock-file watcher
Long-running shell processes	`processes` table fed by hooks on Bash tool calls

Each one is its own primitive with its own discovery and reconciliation logic.

Priority order (based on observed value)

1. ports — most common in dev workflows
2. git_locks — high-impact (data loss risk)
3. processes — broadest applicability
4. db_handles — narrower
5. .git/index.lock — rare but disruptive

Implementation sketch

• New table per primitive in sessions.db
• Detector hook fires on PostToolUse (for Bash/git ops) or via passive watcher (lsof for ports)
• Digest renderer adds a "conflicts" section grouping all primitives
• Auto-release on heartbeat-stale + detector-clear

Acceptance criteria

• At least one new primitive shipped (recommend ports)
• Conflict alert appears in cc.check digest
• Auto-release on heartbeat-stale
• Test coverage for primitive detection logic

[github-actions]

@claude please triage this issue per .github/AI_REVIEW_RUBRIC.md (issue-triage section).