refactor(cli)!: one shared base config with per-surface overlays

`dsh` shipped two config trees that were 43 rows the same: apps/cli/cordis.yml
composed web as 74 flat rows, while the TUI booted examples/tui-agent/cordis.yml
whose single `@deepseek-ai/dsh-tui-demo` row mounted twelve plugins behind a
twenty-key pass-through Config. Neither file was what its location claimed —
apps/cli hardcoded the "example" as the product default and the "demo" bundle
was the application — and every capability change had to be made twice.

- apps/cli/base.cordis.yml holds the 43 shared rows; tui.cordis.yml and
  web.cordis.yml are patch lists stating only what differs per surface
- overlays apply as SIBLING patch lists at one include level, because include
  patches never cross an include boundary. Precedence: base < surface <
  (--config | personal ~/.dsh/config.yaml) < launcher flag/profile patches
- `--config` now applies an overlay INSTEAD OF the personal one, so a demo or
  test tree never inherits the user's route; new `--config-replace` boots a file
  as the entire tree (the old `--config` behaviour). Both survive /resume
- vendor/include: index each `insert`ed row as it is added so a later patch can
  configure or disable it. Upstream built the id index once before the patch
  loop, leaving every surface-only row — the whole TUI front door — silently
  unpatchable from user config. Logged as local modification 8
- session identity moves to dsh-agent-loop's CONFIGURED_AGENT_IDENTITIES_KEY;
  dsh-tui's MAIN_SESSION_ID_KEY is deleted (only the bundle read it)
- delete examples/tui-agent, examples/cordis-agent, packages/examples/tui-demo;
  TUI tests → apps/cli/tests, cordis e2e → packages/cordis/tool-cordis/tests,
  examples/code-mode survives as an overlay leaf
- `dsh web` gains --config, threaded into AppCLIEntry as an extra overlay

Three latent defects surfaced and are fixed here: the TUI captured the optional
sessionQuery service once at construction and could permanently disable /resume
when it won the mount race; the session-store root silently reverted to a
project-local ./.sessions; --config-replace was dropped by the resume handoff.

Verified by booting each tree through the real Loader (TUI 55 entries, web 75,
zero unsettled) rather than reading YAML. All eight terminal snapshots replay
byte-identically; 14/14 PTY smoke, 112/112 snapshots, 25/25 doc-sync, hygiene
and lint clean.

packages/client/AGENTS.md

@@ -86,7 +86,7 @@ If `test:gui` is red on code you did not touch, neither silently fix nor ignore
 Bringing up a new `packages/client/<name>` plugin package (ui-workspace is the latest walked example; ui-sidebar/ui-question are good skeletons to copy):
 
 1. **Package skeleton**: `package.json` (`@deepseek-ai/dsh-client-<name>`, exports `.`/`./invariant`/`./client`/`./src/*`/`./package.json`, `dshClient` manifest, `files` list), `tsconfig.json` (extends `tsconfig.base.client.json`, one `references` entry per workspace dependency plus `support/invariants`), `tsdown.config.ts` (`clientBundle(id, ['lib/types/index.js', 'lib/types/invariant.js'])`), `src/index.ts` (empty node-half apply), `src/invariant.ts` (companion with a real reason), `src/css-modules.d.ts` when using CSS Modules, `README.md` with the Model Experience section.
-2. **Three registration surfaces, all required** (missing any one fails at a different, later point): the `tsconfig.client.json` aggregate `references` entry; a `dshClient` row in `apps/cli/cordis.yml`; an `apps/cli/package.json` dependency (Loader resolves each config-tree package against the composing app's URL — a row whose package is not an `apps/cli` dependency fails to import). `pnpm-workspace.yaml` already globs `packages/*/*`.
+2. **Three registration surfaces, all required** (missing any one fails at a different, later point): the `tsconfig.client.json` aggregate `references` entry; a `dshClient` row in `apps/cli/base.cordis.yml`; an `apps/cli/package.json` dependency (Loader resolves each config-tree package against the composing app's URL — a row whose package is not an `apps/cli` dependency fails to import). `pnpm-workspace.yaml` already globs `packages/*/*`.
 3. **dshClient manifest semantics**: `platform: 'web'` always; `immediately: true` only for stage-one-prefetch infrastructure rows. `inject` lists package-name dependency edges — they are **informational only** (preflight display, HMR diffing); they do not sequence entry activation or apply order. Activation order is cordis fiber inject waiting on *services*, nothing else.
 4. **Registering into another package's slot**: if the declaring host provides no waitable service, your apply's order relative to the host's is unconstrained — a bare `slots.register` into its slot races boot (intermittent `slot "..." is not declared` page failures). Register with declaration-aware deferral: check `ctx.slots.spec(name)`, otherwise `ctx.slots.subscribe(name)` and register on the declaration event (SlotCore supports subscribing ahead of declaration); make the registration idempotent, and unsubscribe + dispose in the effect disposer. Only take a service edge in `inject` when the host actually provides one (ui-question → `'conversation'` is that case).
 5. Rebuild the bundle (`pnpm --filter <pkg> bundle`) before probing a live `dsh web` server — the registry serves `lib/client.js`, not sources.