feat(project): add project update command to edit project metadata

[tarik02]

Motivation

• Provide a single CLI command to update all editable project metadata (title, workspace root, default model selection, default thread environment, and favicon) with explicit clear flags for nullable fields.
• Ensure the CLI enforces sensible validation rules for conflicting flags, workspace-root path semantics (local vs remote), and workspace-relative favicon paths.

Description

• Add a new CLI command implementation at src/cli/projects/update.ts that accepts flags for --title, --workspace-root, model flags, --clear-default-model, --thread-env/--clear-thread-env, and --favicon/--clear-favicon, and rejects conflicting combinations.
• Extend the project application API with updateProject and implement it in src/application/projects.ts to resolve the target project, validate and normalize workspaceRoot for local vs remote environments, validate favicon paths, resolve default model selection via existing model-selection logic, and dispatch a metadata update to the orchestration layer.
• Generalize the construction of the project.meta.update command in src/application/project-commands.ts so callers can provide a sparse patch object and explicit null values are preserved rather than omitted.
• Add a domain error ProjectUpdateValidationError for structured validation failures and wire up a human formatter formatProjectUpdatedHuman and README/changeset entries; register the new subcommand in src/cli/project.ts.

Testing

• Ran git diff --check to validate whitespace and trivial diffs and it succeeded.
• Inspected repository status with git status --short --branch and it completed successfully.
• Attempted git submodule update --init --recursive but cloning the upstream submodule failed due to the environment network/proxy returning HTTP 403, so upstream-dependent dependency resolution could not be completed.
• Attempted pnpm install --offline --ignore-scripts which failed because the unavailable upstream submodule supplies a required patch file, so full dependency install/tests could not be executed in this environment.
• No unit test suite or typecheck run was completed in this environment due to the dependency/submodule failures described above.

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Codex Task

[changeset-bot]

🦋 Changeset detected

Latest commit: 5e73426

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
t3code-cli	Minor

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve the provider during model-only updates

When a project already defaults to provider B, running project update --model <slug> passes the partial update through resolveModelSelection, whose model-only branch selects the first available provider rather than retaining B. This silently changes both fields and can persist a provider/model combination that is incompatible. Partial edits should resolve from the project's existing default selection, as thread metadata updates do, while using the first available provider only when no project default exists.

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