feat: Add semble install

[Pringled]

This PR adds a semble install command. It detects installed coding agents and configures semble globally across three integration types (MCP, instructions, sub-agent). We use tree-sitter for json/jsonc parsing so comments in MCP/settings jsons are preserved.

Here's what the flow looks like in the terminal on runningsemble install (semble uninstall gives the same flow but the reverse (uninstalling whatever is selected)):

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
src/semble/cli.py	100.00% <100.00%> (ø)
src/semble/installer/__init__.py	100.00% <100.00%> (ø)
src/semble/installer/agents.py	100.00% <100.00%> (ø)
src/semble/installer/config.py	100.00% <100.00%> (ø)
src/semble/installer/installer.py	100.00% <100.00%> (ø)
src/semble/version.py	100.00% <100.00%> (ø)

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[Pringled]

@greptileai review

[greptile-apps]

Confidence Score: 4/5

Safe to merge with one follow-up: the uninstall code path needs an end-to-end test.

The installer logic itself is sound and individual helpers are well-tested. The gap is that run("uninstall") is never called end-to-end — the full uninstall flow (remove operations, "not-found" returns through _apply, different UI text, different footer) can silently regress without the test suite catching it. The reviewer specifically asked for e2e coverage of all codepaths, so this missing test is the main concern.

tests/test_installer.py — needs a run("uninstall") end-to-end test to match the run("install") test that already exists.

_{Reviews (3): Last reviewed commit: "Fix toml edgecase" | Re-trigger Greptile}

[greptile-apps]

Confidence Score: 3/5

The install path works correctly for fresh configs; the uninstall path can corrupt pre-existing configs where semble was not the first entry.

The _delete_member function only removes an adjacent comma correctly when semble was inserted as the first member. If semble was added last by another tool (e.g. claude mcp add) and the user then runs semble uninstall, the preceding entry's trailing comma is left in place, making strict-JSON files like .claude.json invalid. The JSON5-based validation guard does not catch it.

src/semble/installer.py — specifically the _delete_member function and the missing test case in tests/test_installer.py.

_{Reviews (2): Last reviewed commit: "Group types/vars" | Re-trigger Greptile}

[Pringled]

@greptileai review this branch again main. Focus on two things:

• e2e testing, ensuring that all the codepaths and combinations resolve correctly or have a clear error message when they fail
• architecture, ensuring that the architecture for the installer is maintainable, easy to understand, and not over-engineered

[stephantul]

Small docs comments, but looks good!