Launch 1M-default Claude models without the [1m] suffix

[Tryanks]

Summary

Since #439 sourced the Claude catalog from the t3code manifest, Opus 5 / Fable 5 sessions launched as claude-opus-5[1m]. Claude Code echoes that id in system/init, but the API reports the bare claude-opus-5 on the first assistant message, so every session opened with a spurious "模型已切换: claude-opus-5[1m] → claude-opus-5" divider.

Upstream t3code appends [1m] unconditionally whenever the contextWindow option resolves to 1m (including 1M-default models) and strips the bracket suffix again on the usage side. We diverge deliberately on the launch id and sync the rest.

Changes

• No suffix at or below the default window. context_window_suffix returns nothing when the selected window does not exceed the model's default, so 1M-default slugs (Opus 5, Fable 5) launch bare. Sonnet 5 / 4.6 (200k default) still get [1m] when 1M is selected. Smaller selections keep compacting early via autoCompactWindow.
• Alias resolution (synced from upstream). Manifest aliases (opus, claude-opus-5.0, …) now parse and resolve case-insensitively to the canonical slug, which is what gets launched. Previously an alias typed as a custom model got no capabilities, effort map, or suffix.
• Divider filter with an explicit suffix list. A launch id carrying a listed context suffix and its bare form count as the same served model when deciding whether to draw the model-changed divider. The list is [1m] and [2m], matched case-insensitively: Claude Code 2.1.273 compares ids with /\[1m\]$/i and its canonical-name normalizer already accepts /\[[12]m\]$/. No other bracket suffix exists in the CLI today, and unlisted ones ([3m]) still count as a real change. No [*] wildcard.

Effort mapping (effortMap, ultracode → xhigh + settings.ultracode, ultrathink as prompt prefix) and the --settings assembly were compared against upstream ClaudeAdapter.ts and already match; the bundled manifest is identical to upstream's current model-manifest.json.

Test plan

• cargo test -p agent (186 passed) — context_window_launch_semantics updated for bare 1M-default launches and alias launches; manifest tests cover alias lookup; strip_context_window_suffix_is_an_explicit_list.
• cargo test -p tcode-core (129 passed) — new served_model_without_1m_suffix_is_not_a_model_change.
• cargo clippy -p agent -p tcode-core --tests clean, cargo fmt --check clean.
• Start an Opus 5 session and confirm no model-changed divider appears on the first reply.