feat(web): idx website and user docs (Astro Starlight)

Landing page plus docs for install, quickstart, config, the stocks and
ownership CLI, output and exit codes, the MCP server and per-agent setup,
agent usage, and an agent-led install page (agents/install.md) that a
coding agent follows from a one-line prompt.

- Every docs page is also served as Markdown at <path>.md; llms.txt and
  llms-full.txt come from starlight-llms-txt; a SKILL.md for skill-based
  harnesses is under /skills/idx/.
- The CLI reference and MCP tools pages are generated from idx --help and
  the tools golden; a new web-generated flake check fails when they drift.
- nix develop .#web provides bun; Cloudflare Pages builds web/ on pushes.
- Package homepage metadata points at https://idx.rasyidanaf.com.
- .cloudflare/ (the cf CLI's account cache) is git-ignored.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/content/docs/cli/output.md

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+---
+title: Output and exit codes
+description: Tables, JSON, errors and exit codes; the contract scripts and agents rely on.
+---
+
+## Formats
+
+| `-o` | Prints |
+| --- | --- |
+| `auto` (default) | a table when stdout is a terminal, compact JSON otherwise |
+| `table` | a table |
+| `json` | one JSON document |
+| `jsonl` | one JSON value per line (one per array item) |
+
+Set the default with `IDX_OUTPUT` or `general.output`. Colour is off whenever
+stdout is not a terminal, and with `--no-color`.
+
+## The contract
+
+- stdout carries only data; warnings, progress and errors go to stderr.
+- On failure stdout is empty.
+- In JSON modes an error is one JSON object on stderr:
+
+  ```json
+  {"error":true,"code":"INVALIDINPUT","message":"invalid input: invalid ticker symbol '../x'"}
+  ```
+
+## Exit codes
+
+| Exit | Meaning | What to do |
+| --- | --- | --- |
+| `0` | success | |
+| `2` | invalid input or config | fix the command |
+| `3` | not found, no data, or no cached data offline | check the ticker or name; go online |
+| `4` | upstream unavailable | retry later |
+| `5` | unsupported | use another command or provider |
+| `1` | anything else | read the message |
+
+## Pipes
+
+```bash
+# names and prices
+idx stocks quote BBCA BBRI | jq -r '.[] | "\(.symbol) \(.price)"'
+
+# the last five daily closes
+idx -o jsonl stocks history BBCA --period 1y | tail -5
+
+# symbols from stdin
+idx stocks screen --filter high-dividend | jq -r '.[].symbol' | idx stocks compare -
+```
+
+`stocks quote` and `stocks compare` read symbols from stdin when given `-`,
+separated by whitespace or commas.

web/src/content/docs/cli/ownership.md

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+---
+title: Ownership
+description: KSEI shareholder data, synced once and queried offline.
+---
+
+The ownership commands work on the monthly KSEI register of holders above 1%
+("Pemegang Saham di Atas 1%") that IDX publishes for every listed company.
+idx keeps it in a local SQLite database, so queries are instant and work
+offline.
+
+## Get the data
+
+```bash
+idx ownership sync
+```
+
+This downloads a maintained snapshot (a few MB, currently the latest three
+months) and installs it. Run it again any time: it does nothing when you are
+already current, and it never replaces a database holding more history than
+the snapshot. `idx ownership releases` lists the months you have.
+
+## Queries
+
+```bash
+idx ownership ticker BBCA               # holders of one stock, with concentration
+idx ownership entity "ANTHONI SALIM"    # every holding of one investor
+idx ownership search salim              # find investor names
+idx ownership changes --from 2026-08-31 --to 2026-09-30
+idx ownership concentration --top 20    # most concentrated stocks (by HHI)
+idx ownership cross-holders --min-tickers 3
+idx ownership graph BBCA --depth 2      # ownership network; --format dot for Graphviz
+```
+
+`changes` lists holders that are new, exited, increased or decreased between
+two releases. `ticker` also reports concentration: the top holder's share,
+the top three, the Herfindahl index (HHI) and the free float (shares held by
+holders below 1%).
+
+## Import reports yourself
+
+The snapshot covers most needs. To load a month it lacks, or older history,
+import IDX's reports directly:
+
+```bash
+idx ownership discover                     # find the latest report URLs on IDX
+idx ownership import --url <xlsx-or-pdf>   # needs curl-impersonate
+idx ownership import --file report.xlsx    # or a local XLSX, PDF, ZIP or TXT
+```
+
+Since June 2026 IDX publishes the register as XLSX; earlier months were PDF
+announcements, which need `mutool`. See [helper tools](/start/install/#helper-tools).
+
+## Entity names
+
+The register spells some investors differently from month to month.
+`idx ownership resolve` lists unresolved names and lets you map an alias to
+an entity or merge two entities.

web/src/content/docs/cli/stocks.md

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+---
+title: Stocks
+description: Quotes, history, company data, analysis and screening.
+---
+
+All `stocks` commands take IDX tickers (`BBCA`, or `BBCA.JK`). Every flag is
+listed in the [command reference](/cli/reference/).
+
+## Quotes and history
+
+```bash
+idx stocks quote BBCA BBRI,BMRI
+idx stocks history BBCA --period 1y --interval 1wk
+```
+
+`quote` takes several tickers, separated by spaces or commas, or `-` to read
+them from stdin. `history` takes `--period` (`1d` to `5y`) and `--interval`
+(`1d`, `1wk`, `1mo`).
+
+## Company data
+
+| Command | What it shows |
+| --- | --- |
+| `profile` | sector, industry, description, contacts and officers |
+| `financials` | income, balance sheet and cash flow statements (`--statement income,balance`) |
+| `earnings` | reported and estimated earnings |
+| `sentiment` | crowd sentiment |
+| `insights` | AI insights from the provider |
+| `news` | recent news |
+
+## Analysis
+
+| Command | What it computes |
+| --- | --- |
+| `technical` | trend, RSI, MACD, moving averages and signals |
+| `growth` | revenue and earnings growth rating |
+| `valuation` | P/E, P/B, ROE, net margin and EV/EBITDA, with a rating |
+| `risk` | debt to equity, current ratio and ROA, with a rating |
+| `fundamental` | growth, valuation and risk in one report |
+| `compare` | `fundamental` for several tickers side by side |
+
+```bash
+idx stocks fundamental BBRI
+idx stocks compare BBCA BBRI BMRI
+```
+
+## Screening
+
+```bash
+idx stocks screen --filter high-dividend --limit 20
+```
+
+Filters: `top-performers` (default), `worst-performers`, `high-dividend`,
+`low-pe`, `52w-high`, `52w-low`, `high-volume`, `large-cap`.
+
+Screen results pipe straight into `compare`:
+
+```bash
+idx stocks screen --filter high-dividend | jq -r '.[].symbol' | idx stocks compare -
+```
+
+## Providers
+
+MSN is the default for quotes, company data and screening; Yahoo serves
+price history. Switch with `IDX_PROVIDER=msn|yahoo` and
+`IDX_HISTORY_PROVIDER=auto|yahoo|msn`, or the matching
+[config keys](/start/config/).