v1.24.0 — memory scope isolation (stop cross-project context bleed)

Added

• Memory scope isolation (fixes cross-project context bleed). Ambient context - the Claude Code UserPromptSubmit hook, hippo context, GET /v1/context, and MCP hippo_context - no longer injects memories owned by OTHER projects into the active session. Every memory now carries an origin_project (a project name = owned by that project, '' = user-global and injectable everywhere, NULL = legacy pre-v39 row, treated as other-project). Origin is stamped automatically from the store's location at write time; migration v39 backfills existing rows from store location and shared:<project>: sources. Escape hatches: hippo context --cross-project (rendered under a demarcated "Other-project memory" section), cross_project=1 on /v1/context, and config contextProjectIsolation: false.
• Secret hard veto. New content/tag secret detection (provider-bounded patterns + secret/api-key/token/... tags). Secrets are never auto-shared or explicitly shared to the global store (hippo share refuses, hippo sleep skips), never synced down by hippo sync, and never ambient-injected outside their owning project - not even with --cross-project or isolation disabled. Origin-less secrets never ambient-inject at all. Explicit hippo recall still returns them: recalling a secret is a deliberate act.
• Context assembly now applies the same envelope default-deny as recall. Private scopes (*:private:*) and quarantine buckets never inject into ambient context (previously only hippo recall/MCP recall enforced this).
• hippo sync --cross-project re-includes other-project rows when syncing global memories down; the default now skips them (secrets always skipped). syncGlobalToLocal preserves origin_project on copies.

Changed

• Behavior change for existing installed hooks (intended): the UserPromptSubmit hook command is unchanged and keeps working, but its injected content is now project-scoped. If you relied on seeing other projects' memories everywhere, set contextProjectIsolation: false in config.json or use --cross-project explicitly.
• ContextResult entries gain origin and category (project | user-global | cross-project); the CLI JSON format exposes both.
• shareMemory stamps the canonical origin_project on global copies (derived from the entry's own write-time stamp, not the local path basename).
• Migration v39 (schema 38 -> 39): adds memories.origin_project + evidence-based backfill. Additive and idempotent; no data is removed.
• Upgrade in lockstep on shared machines. v39 stamps min_compatible_binary: 1.24.0 on every store it migrates, including the shared ~/.hippo global store. Any still-installed pre-1.24.0 hippo binary (pinned project dependency, old plugin bundle, stale hook install) will then refuse to open that store by design - the refusal is what prevents an old binary from silently leaking cross-project rows again. Upgrade all hippo installs on the machine together.