Feature: more customizable startup

[jmcphers]

Replaces run_in_shell with more ways to customize kernel startup, either with a command (like module load or conda activate) or a script.

Also, some chores:

• migrate to newer version of OpenAPI code generator
• migrate hyper 0.1 => hyper 1.0 (some refactoring needed)
• break up increasingly monolithic kernel_session.rs
• use a script rather than hand edits to remove TLS/openssl dependencies

[Copilot]

Pull Request Overview

This PR replaces the run_in_shell boolean parameter with a more flexible startup_environment enum that supports multiple kernel startup modes: none (direct), shell (login shell), command (preflight command), and script (startup script). The PR also includes major dependency upgrades from hyper 0.14 to 1.6 and swagger 6.5.0 to 7.0.0-rc2, with corresponding refactoring throughout the codebase.

Key changes include:

• New API fields startup_environment and startup_environment_arg replacing run_in_shell
• Modularized kernel session code with separate modules for startup, lifecycle, environment, process management, etc.
• Shell command escaping utilities for secure command execution
• Startup markers to detect failure points during initialization
• Comprehensive test coverage for new startup modes
• Hyper 1.x migration with updated service traits and body handling

Reviewed Changes

Copilot reviewed 49 out of 51 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
kallichore.json	Adds startupEnvironment enum and startup_environment_arg field to API schema
scripts/remove-tls-deps.sh	New script to remove TLS dependencies from generated API code
scripts/regen-api.sh	Updated to call TLS removal script after API generation
crates/kcserver/src/kernel_session/*.rs	Modularized kernel session into separate concerns: startup, lifecycle, environment, process, shell wrapper, connection, handshake, utils
crates/kcserver/src/server.rs	Migrated to hyper 1.x with manual connection handling and service trait updates
crates/kcserver/src/websocket_service.rs	Updated for hyper 1.x body and service changes
crates/kcserver/tests/*.rs	Updated all tests to use new startup_environment API, added tests for command and script modes
crates/kallichore_api/src/server/mod.rs	Extensive hyper 1.x migration with new body types and service implementations
crates/kallichore_api/src/context.rs	Simplified authentication context without separate Authorization layer
crates/kcserver/Cargo.toml	Updated hyper, swagger, hyper-util, hyperlocal dependencies
crates/kcclient/src/main.rs	Updated to use new startup_environment API

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