docs(v1): add SECURITY.md + versioning policy; fix LICENSE and stale overlay gotcha

- Add SECURITY.md: private disclosure path, supported versions, known limitations.
- Add docs/versioning-policy.md defining what 1.0 SemVer covers (CLI + documented env vars are public; HTTP/SSE API, on-disk state, and experimental features are internal/unstable).
- LICENSE: '2024 Claudeman Contributors' -> '2024-2026 Codeman Contributors'.
- CLAUDE.md: fix the stale xterm-zerolag-input 'duplicated in app.js' gotcha (it is single-source now -> gitignored vendor bundle via postinstall.js/build.mjs); add versioning + security pointers; minor /init nav fixes (image-input load order, server.ts marker).
- README: link SECURITY.md + the versioning policy.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/versioning-policy.md

@@ -0,0 +1,78 @@
+# Versioning & Stability Policy
+
+Codeman follows [Semantic Versioning](https://semver.org/) (`MAJOR.MINOR.PATCH`),
+managed via `@changesets/cli` (see the COM workflow in `CLAUDE.md`).
+
+This document defines **what the version number actually promises** — i.e. which
+surfaces are covered by SemVer and which are explicitly not. It exists because
+"1.0" is a commitment to stability, and an undocumented public surface invites
+incompatible client assumptions we would then be pressured to keep.
+
+> **Status:** draft for the 1.0 cut. The central decision below — that the HTTP/SSE
+> API is *not* SemVer-covered — should be confirmed by the maintainer before 1.0,
+> since it determines whether a number of in-flight cleanups are "breaking."
+
+## What SemVer covers (the public, stable surface)
+
+A **MAJOR** bump is required to break any of these after 1.0:
+
+1. **The CLI.** Command names, documented flags, and their behavior for
+   `codeman <command>` (published to npm as `aicodeman`; invoked as `codeman`).
+   This is the package's actual public entry point (`bin`).
+   - *Note:* the npm package name vs. invoked command name (`aicodeman` vs
+     `codeman`) is a known inconsistency to resolve **before** 1.0 — renaming
+     either after 1.0 is itself a breaking change.
+2. **The published `xterm-zerolag-input` library**, but on **its own version
+   line** — it is versioned and released independently of the Codeman app. Its
+   1.0 status is a separate decision; the Codeman app reaching 1.0 does *not*
+   imply `xterm-zerolag-input` is 1.0.
+3. **Documented environment variables** that configure deployment:
+   `CODEMAN_PASSWORD`, `CODEMAN_USERNAME`, `CODEMAN_HOST`, `CODEMAN_PORT`,
+   `CODEMAN_INSTANCE`, `CODEMAN_ALLOWED_HOSTS`, `CODEMAN_DATA_DIR`,
+   `CODEMAN_TMUX_SOCKET`, and the `--host` / `--port` / `--https` CLI flags.
+   Removing or changing the meaning of one of these is breaking.
+
+## What SemVer does NOT cover (internal surfaces — may change in any release)
+
+These may change in a **MINOR** (or even PATCH) release without a MAJOR bump:
+
+1. **The HTTP API and SSE event registry** (`/api/...`, the ~120 SSE event
+   types). This is an **internal protocol between the server and its own bundled
+   web frontend**, not a published client API. There is no OpenAPI spec, no
+   published client, and no versioned `/api/v1` namespace. If you script against
+   these endpoints, **pin to an exact Codeman version** — they can change between
+   minors (response shapes, status codes, event names). Standardizing the error
+   envelope and HTTP status codes is explicitly reserved as a non-breaking
+   internal change under this policy.
+2. **The `~/.codeman/` state file formats** (`state.json`, `settings.json`,
+   `mux-sessions.json`, etc.). We make a **best-effort** to migrate existing data
+   forward (and have done so across renames), but the on-disk schema is not a
+   stable contract — do not write tooling that depends on its exact shape.
+3. **Internal TypeScript modules.** The npm package is CLI-only; `import`ing it
+   programmatically is not supported (there is no stable library entry point).
+4. **Experimental / opt-in features**, regardless of the app's version:
+   Gesture Control (beta), Agent Teams
+   (`CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1`), and anything labeled experimental
+   in the UI or docs. These may change or be removed at any time.
+
+## Deprecation policy
+
+When we need to change a covered surface:
+
+- Prefer **additive** changes (new flag/env var/command) over breaking ones.
+- A covered surface slated for removal is **deprecated first** — it keeps working
+  for at least one MINOR release with a runtime warning and a `CHANGELOG.md` note
+  pointing to the replacement — then removed in the next MAJOR.
+- Back-compat migration shims (e.g. the historical Claudeman→Codeman data/socket
+  migration) are kept until a MAJOR boundary, then may be dropped.
+
+## Pre-1.0 (`0.x`) caveat
+
+Until 1.0 ships, **any release may contain breaking changes** per SemVer's `0.x`
+allowance. The commitments above take effect at `1.0.0`.
+
+## See also
+
+- `CLAUDE.md` — the COM release workflow (changesets, version bump, deploy)
+- `SECURITY.md` — security reporting and the supported-version policy
+- `docs/security-architecture.md` — the full trust model