docs(release): bump displayed version to 0.12.0 (site + install snippets) (#160)

v0.12.0 is published across crates.io / npm / PyPI / WASM / Go, so update
the version surfaces that the release pipeline doesn't touch:

- web/src/lib/site.ts: SITE.version 0.11.0 → 0.12.0 — the single source of
  truth the marketing site reads (hero badge, docs header, SDK showcase
  cards, structured-data softwareVersion).
- README.md / docs/embedding.md / docs/ask.md: the Rust install snippets
  pinned `sqlrite-engine = "0.11"` / `sqlrite-ask = "0.11"`. Bump to "0.12"
  so the documented pin installs the current release.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: joaoh82

README.md

@@ -214,8 +214,8 @@ Expressions in `WHERE` and `UPDATE`'s `SET` RHS:
 
 ```toml
 [dependencies]
-sqlrite-engine = "0.11"
-sqlrite-ask    = "0.11"
+sqlrite-engine = "0.12"
+sqlrite-ask    = "0.12"
 ```
 
 ```rust

docs/ask.md

@@ -131,8 +131,8 @@ If `SQLRITE_LLM_API_KEY` is missing, the panel surfaces a clean "missing API key
 
 ```toml
 [dependencies]
-sqlrite-engine = "0.11"
-sqlrite-ask    = "0.11"
+sqlrite-engine = "0.12"
+sqlrite-ask    = "0.12"
 ```
 
 ```rust

docs/embedding.md

@@ -153,8 +153,8 @@ The retryable-error branch is the headline new flow: pick a backoff policy that
 [dependencies]
 # `ask` is a default feature on sqlrite-engine; opt out with
 # default-features = false if you don't want the LLM stack pulled in.
-sqlrite-engine = "0.11"
-sqlrite-ask    = "0.11"
+sqlrite-engine = "0.12"
+sqlrite-ask    = "0.12"
 ```
 
 ```rust

web/src/lib/site.ts

@@ -1,7 +1,7 @@
 export const SITE = {
   url: "https://sqlritedb.com",
   twitterHandle: "@CodePolyglot",
-  version: "0.11.0",
+  version: "0.12.0",
   repo: "https://github.com/joaoh82/rust_sqlite",
   discord: "https://discord.gg/dHPmw89zAE",
   docsRs: "https://docs.rs/sqlrite-engine",