fix: skip API key check for local providers and fix /v1 endpoint suffix

[bluzername]

Problem

Two bugs from issue #4 when using mnemex with Ollama or other local embedding providers:

Bug 1: mnemex index requires OpenRouter API key even when using Ollama/local provider. Running mnemex index after configuring Ollama gives:

Error: OpenRouter API key not configured.
Run 'mnemex init' to set up, or set OPENROUTER_API_KEY.

This makes no sense because I configured Ollama as my embedding provider, not OpenRouter.

Bug 2: The init wizard saves localEndpoint without /v1 suffix, but the embeddings client sends requests to {localEndpoint}/embeddings which gives 404. The LLM endpoint is correctly set to http://localhost:11434/v1 by the same wizard - inconsistent behavior.

What I changed

Bug 1 fix - src/config.ts:

• Added isLocalEmbeddingProvider(projectPath) function that checks if the project config has embeddingProvider set to ollama, lmstudio, or local
• Uses the existing loadProjectConfig() to read the setting

Bug 1 fix - src/cli.ts:

• Imported isLocalEmbeddingProvider
• Updated the API key check in index command (line ~725): added && !isLocalEmbeddingProvider(projectPath) so local providers skip the check
• Updated the API key check in search command (line ~1509): same fix
• Left the benchmark command check unchanged (benchmarks are dev tools that may need cloud APIs regardless)

Bug 2 fix - src/cli.ts:

• When saving config for local provider, the endpoint now gets /v1 appended if not already present: embeddingEndpoint.endsWith("/v1") ? embeddingEndpoint : embeddingEndpoint + "/v1"
• This matches how lmstudio endpoint already defaults to http://localhost:1234/v1

Not addressed

Bug 3 from issue #4 (hardcoded wasm path for global install) - this one needs deeper investigation into the tree-sitter wasm resolution logic which I didnt want to mix into this PR.

Closes #4 (bugs 1 and 2)