Add expiring agent support shell invitations

[zzj3720]

Summary

Adds ssh-session: the same capabilities and request handling as ssh-shell, with additional deadline admission and active-session expiry checks. Existing ssh-shell behavior and object are unchanged.

The bootstrap now uses the generic hosted delegation API from synchronicity #148:

• Keep only tools/session-client.py for consent, verified runtime/program downloads, local device-key generation, foreground node ownership and expiry/cleanup.
• Print the public key and exact registration JSON. The authorized operator submits them to the new CP PUT endpoint; the managed DP signs the existing delegation record. The operator revokes through CP DELETE.
• Delete private invitation generation, SQLite database packaging, bearer ticket storage, short-link server and their obsolete tests. No controller/node secret or CP credential is embedded in a distributed script.
• The socket pins the controller public key; the temporary node trusts only that controller. The controller must be a named member of the hosted network.

Validation

• Authorization/deadline C tests, capability/handler parity, six bootstrap tests and two build tests pass.
• Canonical object checksums and capability loading passed in the previous exact-head CI; object bytes are unchanged in this bootstrap update.
• Real macOS v0.1.10 download/checksum, local key generation, offline trust setup, online daemon startup and socket activation passed. Inspected the temporary node, stopped it with Ctrl-C, and verified removal of its temporary directory.
• Full live CP→DP→bootstrap connection is not yet validated: the new API is not deployed. The companion PR's 343 Gleam tests, 47 DP library tests, local clippy and independent review pass; CI remains in progress.

Boundaries

No invitation/token service, persistent installation or production deployment. Short-command distribution is left to the calling application; command length is not restricted. The bootstrap prints public registration data rather than claiming that local readiness proves network admission.

The shell has OS-user privileges; it is not a sandbox. Deadline/revocation cannot undo changes or guarantee cleanup of detached descendants. Network delegation expiry/revocation and application connection shutdown are separate. Linux bootstrap behavior remains unvalidated.

Production source boundary src/, include/session-deadline.h, tools/: +237 / -4, net +233, total 241 changed lines; excludes tests/docs/CI/generated objects.

[zzj3720]

Updated to cf0e9e9 with canonical Docker objects/checksums and signal-safe teardown. Independent agent re-review of this exact head found no blockers (not a GitHub approval). Local authorization/deadline tests, five session-tools tests and two build tests pass. Canonical object loads and has only a shell-process capability. Fork exact-head CI passed; upstream PR check is still running. Real macOS v0.1.10 tests covered generation, consent, temporary node startup, agent SSH login and forced expiry of an active shell; test nodes, invitation secrets and grants were removed. Linux runtime and signal-driven E2E remain unverified. Production source boundary src/, include/session-deadline.h and tools/: +324 / -4, net +320, total changed 328 lines; excludes tests/docs/CI/generated binaries.

[zzj3720]

Added short-command delivery at fcb9a7c. make-session.py can now publish atomically into a private local store and produce an HTTPS curl-to-sh command bounded to 100 characters (74 with the documented example domain). The loopback origin is read-only, expiry-gated, no-store/no-referrer and token-log-free; a human-operated HTTPS proxy is required for public deployment. Added six tests covering expiry, malformed/missing/symlink tickets, no remote issuance, token logging, command length, private permissions, atomic collision refusal, real curl-to-sh execution and PTY consent. Full local test suite passes. macOS end-to-end with real v0.1.10 runtime (verified cached release archive), a local HTTP origin and real SSH succeeded; Ctrl-C stopped the temporary node, and test delegation/store were cleaned up. Independent full-thread re-review and exact-head CI are in progress. Production boundary unchanged: +544 / -4, net +540, total 548 changed lines. No production service has been deployed.

[zzj3720]

Latest clarification applied at 0a200f0: command length is advisory only. Long HTTPS bases still generate normally; actual length is printed, and ticket entropy/HTTPS validation remain intact. Independent full-thread re-review found no blockers. All local tests pass, including explicit acceptance of commands over 100 characters. Exact-head CI is pending. Updated cumulative production-source counts (same boundary): +542 / -4, net +538, total changed 546 lines.

[zzj3720]

Updated at 531c9c0: ssh-session retains ssh-shell capabilities and request handling, including scoped SFTP/tree-write; only deadline checks and program name differ. Canonical object/checksums and security documentation are updated. Capability/handler parity regression and all local tests pass. Independent agent re-review found no blockers (not a GitHub approval). Exact-head Check sources and committed objects CI passed. Actual SFTP transfers and deadline behavior with the rebuilt object were not re-exercised. Production boundary src/, include/session-deadline.h, tools/: +537 / -4, net +533, total 541 changed lines, excluding tests/docs/CI/binaries. No merge or deployment performed.

[zzj3720]

Latest 03b4394 removes redundant invitation/database packaging and download-server tooling in favor of hosted delegation PUT/DELETE from synchronicity #148. Only the user bootstrap remains. Independent thread-driven agent re-review found no blockers (not a GitHub approval); fixed the documented SSH destination to be device-key-specific so repeat sessions preserve host-key verification. Local tests and real macOS bootstrap/download/activation/Ctrl-C cleanup passed. Full live hosted-registration connection remains unvalidated; companion API is not deployed. Exact-head CI pending. Production boundary src/, include/session-deadline.h and tools/: +237 / -4, net +233, total 241 lines; excludes tests/docs/CI/binaries.