Inject 1Password secrets, system prompts, session naming, and restructure nixhome modules

[DimmKirr]

Changes

DevCell Go implementation: Inject 1Password secrets, system prompts, session naming, and restructure nixhome modules

• feat(cmd): remove cell chrome command — cookie encryption mismatch between macOS host and Linux container makes feature non-viable
• feat(cmd): add --session-name global flag and DEVCELL_SESSION_NAME env var for persistent home override with priority: DEVCELL_SESSION_NAME → TMUX_SESSION_NAME → "main"
• feat(cmd): add cell init . to scaffold project-level .devcell.toml with overwrite confirmation
• feat(config): add ResolveAvailablePorts to auto-bump VNC/RDP ports when preferred ports are occupied
• feat(op): add 1Password item resolution via op item get — fields become container env vars passed securely via -e KEY
• feat(runner): inject Claude Code system prompt via --append-system-prompt describing container environment, bind mounts, and host path mappings
• feat(runner): auto-detect git identity from host git config when no explicit env or [git] toml section set
• feat(runner): display base/user image versions on error and in debug mode
• feat(cfg): add [op] section with items for 1Password secret injection, [cell] gui field, composable stack/modules config
• feat(scaffold): update devcell.toml template with composable stacks config — stack (base/go/node/python/fullstack/electronics/ultimate) + modules addons
• feat(scaffold): add project-level .devcell.toml template, RegeneratePackageFiles for --build
• refactor(nixhome): rename profiles/ → stacks/, restructure LLM tools into llm/ module (claude.nix, codex.nix, opencode.nix, mcp.nix)
• refactor(nixhome): replace inline entrypoint scripts with shell fragments in modules/fragments/
• refactor(nixhome): delete managed-claude.nix, managed-mcp.nix, managed-opencode.nix — replaced by llm/ modules
• feat(nixhome): add financial, news, travel, scraping, mise modules with MCP server configs
• feat(nixhome): add HTTP MCP server support for Linear, Notion in infra module
• chore(nixhome): improve LD_LIBRARY_PATH handling with baked nix-ld-library-path file and layered export
• chore(runner): support InheritEnv keys to pass env var names without values to docker run
• chore(runner): pin container to exact image ID to prevent tag races from concurrent builds
• chore(images): refactor entrypoint.sh to source entrypoint.d/*.sh fragments with error logging
• chore(docker-bake.hcl): update build matrix, cache scopes, platform overrides for local targets
• chore(web): redesign homepage with tool logos, updated copy, feature cards for secrets/MCP/VNC
• test(config): add DEVCELL_SESSION_NAME priority, port resolution, and idempotency tests
• test(runner): add system prompt generation and docker run arg verification tests
• test(cfg): add [op] section, GUI field, and merge semantics tests
• test(gui): add clipboard sync test for RDP cliprdr channel
• test(runtime): add nix-ld-library-path and LD_LIBRARY_PATH verification tests
• refactor(cmd): use version.Full() everywhere, add PersistentPreRun debug version output