feat: add a secure durable packet inbox

[coldlogicAI]

Summary

• add an explicit local filesystem durable inbox around existing immutable .notchpkt packets
• add simple CLI flow: inbox init, send, list, pull/import, and ack
• add matching vendor-neutral MCP tools and Grok setup instructions for cross-model clients
• preserve typed reply lineage and normal 3Notch import/check behavior

Usability and simplicity

• one shared root, one local address per store, one-purpose commands
• no daemon, database, account, hosted relay, polling loop, chat layer, or model invocation
• deterministic retry identity and retained acknowledgements make failures inspectable
• a small transport adapter boundary and stable MCP schemas prepare a later authenticated remote/plugin layer without vendor branches in the core

Security and traces

• registered recipients only; typo addresses fail
• sender-side archive, schema, artifact hash, size, and credential-pattern checks before shared writes
• private and seed packets are blocked
• hash verification before pull/import; corruption is retained and marked rejected
• bounded compressed/unpacked archive work plus strict tar checksum, numeric field, padding, duplicate path, traversal, and trailing-data rejection
• local lifecycle audit events contain IDs, hashes, routing labels, byte counts, states, actor/source, and error codes, never packet content
• addresses are documented honestly as routing labels, not authentication or encryption

Verification

• clean npm ci
• lint, type-check, and production build
• 234/234 tests across 78 files
• 23/23 e2e tests across 11 files
• 20-way simultaneous send and 10-way simultaneous import tests
• packed @3notch/cli@0.6.0 installed into an empty prefix and completed request -> import -> typed reply -> import -> ack with both stores passing notch check
• npm audit: 0 source vulnerabilities and 0 installed-package vulnerabilities

Not included

Hosted transport, OAuth, signatures, encryption, team ACLs, delete/retention, background delivery, distributed sync guarantees, or automatic model-to-model calls.

[coldlogicAI]

Fixed both merge blockers in commit de09211.

1. Rejected delivery recovery

• Receiver-side size-policy failures now remain retryable instead of becoming terminal rejections.
• After the receiver raises its configured limit, the existing delivery can be pulled and imported normally.
• Legacy deliveries already rejected with NOTCH_ARCHIVE_TOO_LARGE or NOTCH_PACKET_TOO_LARGE recover after successful revalidation and clear their stale rejection metadata.
• A genuinely rejected delivery can no longer return a false-success idempotent resend. The sender receives NOTCH_INBOX_STATE_INVALID and must send a corrected packet with a new packet ID.

2. Mailbox clutter tolerance

• Inbox listing now ignores entries outside the managed delivery_<24 hex> namespace, including sync-conflict copies and stray files.
• Entries that claim a valid managed delivery ID still fail closed when malformed.

Regression coverage

Added tests for:

• low receiver limit → failed pull remains pending;
• raised receiver limit → same delivery imports successfully;
• legacy size-rejection recovery and rejection-field cleanup;
• rejected resend returning an explicit error instead of success;
• adapter and CLI listing with sync-conflict clutter;
• malformed managed delivery entries still failing closed.

Verification

• lint: passed
• type-check: passed
• production build: passed
• tests: 235 passed across 78 files
• e2e: 23 passed across 11 files
• built CLI smoke check: passed
• GitHub CI: passed on Ubuntu and macOS with Node 20 and 22

PR #7 is currently clean and mergeable.